@Ichabod Building facilities on just ‘activated’ neutrals indeed is an unresolved issue, that is part of @gamerman01 's list in this topic:
https://www.axisandallies.org/forums/topic/21330/triple-a-g40-comprehensive-list-of-currently-unresolved-issues
It is noted as issue at the Github-repository of that map, too:
https://github.com/triplea-maps/world_war_ii_global/issues/2
Of course - as you correctly pointed out - it is not allowed, as the rulebook clearly states "Place new facilities in any eligible territory that you have controlled since the start of your turn. " (Rulebook Pacific 1940.2, page 22).
I can’t say whether this will ever be fixed. In the meantime you could tell your opponents in advance that TripleA does not remove the player’s responability of knowing the rules. That is what the game notes of this map say in the “Disclaimer”-section, too.
TripleA has known issues and after all those years we still discover new ones. It is an ongoing process of improvement. However everybody’s time is limited and there is a lot to do … :slightly_smiling_face: