Hi Leonardo:
Thanks for the heads-up on typos in some FS9 default file names in my posts above (they should all be corrected now).
[EDITED]
It was apparent to me from your statements in the OP above, that you may have had a goal of achieving not only a more accurate "shape" to the topography, but also the shorelines of Futuna and Alofi islands.
Additionally, it seemed likely that you may have intended to enhance other islands along the course of your flights in FS9, so I thought you might benefit from learning how to make accurate terrain mesh, and how to allow it to be displayed properly by making necessary modifications to COPIES of default FS9 terrain BGLs.
Please be assured that we will proceed promptly into the process of making your replacement enhanced terrain mesh after first enabling display of the entire extent of the islands, via the above process of making necessary modifications to COPIES of default FS9 terrain BGLs.
I will soon be showing you where to personally- and at your own discretion- directly access the newer, and more accurate, SRTM data that is 'cleaned' (and which, in spite of the 'current' state of incremental improvement from the original 'raw' SRTM data made available years ago, may still require re-assignment of elevation values along shorelines via the editing process in SB9 and/or SBX).
This 'may' involve edits to both the VTP shoreline poly-line elevations as well as the simpler process of setting surrounding LOD-13 quad LWM Hydro polygon elevations to 0 Meters AMSL.
Depending on how accurate you may wish to make your version of the above islands, further modifications may be needed in the rendering of the terrain mesh data along shoreline areas due to ongoing SRTM source data anomalies, by use of "sloped flattens" implemented as LWM3 triangular polygons.
I also plan to help you find a way (via freeware GIS applications) to merge the legacy SRTM data with the newer SRTM data in order to achieve the minimum LOD-related source data Geographic coverage extents required by FS2Kx SDK Resample versions to allow output of 'fully functional' terrain mesh BGLs that are successfully displayable in FS9 at run time.
So, with some patience, you'll soon be able to "make a mesh of things" whenever you wish.
[END_EDIT]
I have only a few minutes free on the road this afternoon, and I know your time zone is 6 hours ahead of USA central time, so i'll suggest initially that you study the SB9 and SBX *.CHM "Help" file sections on working with Lines and Polygons.
Those sections explain how to activate the features for editing vertices by inserting, deleting, moving, smoothing, sampling inter-point distances to increase / decrease point density along poly-lines etc.
After 'Appending' the above referenced COPIES of default FS9 BGLs to SB9, save a backup copy of the "*.SBP" project info file under a new name that includes 'SB9' somewhere in the file name, and test your skills at editing the separate FS9 VTP shoreline poly-line and the edges of the LWM 'Hydro' polygons.
BTW: IIRC, you must perform manual incremental saves of your work to the SBP project file periodically in SB9, whereas SBX appears to perform those incremental 'saves' automatically.
Alternatively, you can immediately Export a *.SBX complete project file and Import it into SBuilderX, then test your skills at editing the separate FS9 VTP shoreline poly-line and the FS9 edges of the LWM Hydro polygons.
In either case, you may find it easier to work with the Hydro polygon vertices first, by dragging the shoreline poly-line(s) off to the side to be edited or replaced later on.
FYI: I will have to test further, the method for Export of a BLN file from SBuilderX for Import back into SB9, as the initial test I performed in SB9 with Import of a SBX that was Exported by SBuilderX failed.
This can 'probably' be worked around by editing vertex density before Export from- or attributes for GUIDs in the SBX file after Export from- SBuilderX, so I'll have to work with that upon my return later today.
I must resume my travels now, so I'll check back on this thread soon.
GaryGB
Thanks for the heads-up on typos in some FS9 default file names in my posts above (they should all be corrected now).
[EDITED]
It was apparent to me from your statements in the OP above, that you may have had a goal of achieving not only a more accurate "shape" to the topography, but also the shorelines of Futuna and Alofi islands.
Additionally, it seemed likely that you may have intended to enhance other islands along the course of your flights in FS9, so I thought you might benefit from learning how to make accurate terrain mesh, and how to allow it to be displayed properly by making necessary modifications to COPIES of default FS9 terrain BGLs.
Please be assured that we will proceed promptly into the process of making your replacement enhanced terrain mesh after first enabling display of the entire extent of the islands, via the above process of making necessary modifications to COPIES of default FS9 terrain BGLs.
I will soon be showing you where to personally- and at your own discretion- directly access the newer, and more accurate, SRTM data that is 'cleaned' (and which, in spite of the 'current' state of incremental improvement from the original 'raw' SRTM data made available years ago, may still require re-assignment of elevation values along shorelines via the editing process in SB9 and/or SBX).
This 'may' involve edits to both the VTP shoreline poly-line elevations as well as the simpler process of setting surrounding LOD-13 quad LWM Hydro polygon elevations to 0 Meters AMSL.
Depending on how accurate you may wish to make your version of the above islands, further modifications may be needed in the rendering of the terrain mesh data along shoreline areas due to ongoing SRTM source data anomalies, by use of "sloped flattens" implemented as LWM3 triangular polygons.
I also plan to help you find a way (via freeware GIS applications) to merge the legacy SRTM data with the newer SRTM data in order to achieve the minimum LOD-related source data Geographic coverage extents required by FS2Kx SDK Resample versions to allow output of 'fully functional' terrain mesh BGLs that are successfully displayable in FS9 at run time.
So, with some patience, you'll soon be able to "make a mesh of things" whenever you wish.

[END_EDIT]
I have only a few minutes free on the road this afternoon, and I know your time zone is 6 hours ahead of USA central time, so i'll suggest initially that you study the SB9 and SBX *.CHM "Help" file sections on working with Lines and Polygons.

Those sections explain how to activate the features for editing vertices by inserting, deleting, moving, smoothing, sampling inter-point distances to increase / decrease point density along poly-lines etc.
After 'Appending' the above referenced COPIES of default FS9 BGLs to SB9, save a backup copy of the "*.SBP" project info file under a new name that includes 'SB9' somewhere in the file name, and test your skills at editing the separate FS9 VTP shoreline poly-line and the edges of the LWM 'Hydro' polygons.
BTW: IIRC, you must perform manual incremental saves of your work to the SBP project file periodically in SB9, whereas SBX appears to perform those incremental 'saves' automatically.
Alternatively, you can immediately Export a *.SBX complete project file and Import it into SBuilderX, then test your skills at editing the separate FS9 VTP shoreline poly-line and the FS9 edges of the LWM Hydro polygons.
In either case, you may find it easier to work with the Hydro polygon vertices first, by dragging the shoreline poly-line(s) off to the side to be edited or replaced later on.

FYI: I will have to test further, the method for Export of a BLN file from SBuilderX for Import back into SB9, as the initial test I performed in SB9 with Import of a SBX that was Exported by SBuilderX failed.
This can 'probably' be worked around by editing vertex density before Export from- or attributes for GUIDs in the SBX file after Export from- SBuilderX, so I'll have to work with that upon my return later today.
I must resume my travels now, so I'll check back on this thread soon.

GaryGB
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