I have downloaded the indicated aircraft. The link in "msg696" to the flight plans was broken.
First, it is important to recognize that the aircraft file is not a repaint, it is an entire aircraft. AIFP's "Install Repaints" function is intended to install repaints, i.e., additional titles and textures for previously installed aircraft, not complete aircraft. While you could have forced AIFP to treat the file as a repaint, neither the Model folder nor the .air file would have been installed - which may explain why you don't see any AI aircraft.
Nonetheless, the situation was fortuitous since my investigation did reveal a minor coding error that resulted in a warning similar to the first error message you reported. (I was unable to find any place in AIFP which issued the exact error message you reported. The message I received was "The [FltSim.x].txt data for ______ is invalid/incomplete or the designated texture folder is missing from the repaint archive." In fact, it was the unnamed texture that was responsible for the message. When you report issues, its important to be factual.
Without knowing further details, I am unable to comment on the balance of your situation.
Don