Not now, because I already tried to change it in "300" for the peltasts/longbowmans and still crashed, thus I was thinking the problem is in the number of shooting frames. if I understand well, there is no way to create a shooter capable to replace ANY creature, but have to specify which, otherwise it will crash.

Do you have a working palette of HoMM units? I extracted and worked on the succubus then compared with yours and there is big difference in colors. I guess you painted it also (arms skin in red), but still the palette is not same.