Solarius, my Knowledge of github if near to zero, but I can try to update all the rulesets in the repository to 1.9.6 at least (making the corresponding branch), and try to post updates every time you update the pack.
BTW. the MIB base missions is intended to work as a infinite time landing? Or it is just a workaround?.
I search for siteType: in all the .rul in X-piratez and don´t get any hit. Maybe they use something different?.
To end, as far as I understand, STR_ALIEN_BASE_ASSAULT for alien infiltration is because at the end of the infiltration mission, aliens generate a base, and you need that siteType: in every mission that generate at the end a place. TBH, I don´t know how the code works (Or any c++). It is just my guessing but, alien terror missions should not have a siteType: too?.