First of all, use Magic.TXD to edit the .txd files

Now with Magic.TXD you will no longer have to compress some specific textures again, but make sure to edit the .txd file well!

If you want to adapt or create a livery, the most important thing you should know is that you must combine the "Tailnight_on" texture with "ASCRJ700_FUSETAIL_C", it must be DXT5 compressed alpha texture