Hi PsiSoldier. This is a mod for the previous game in the series, Space Empires IV.
In SE4, the AI is ok if not great, and the current version of my Proportions mod (that this thread is about) actually interferes a bit with the AI, in that it adds things without telling the AI how to use them correctly. (Nonetheless, a few players have played against the AI anyway and found some challenge despite that.)
In SE5, the version you asked about, I haven't really played it since it first came out, either. There are quite a few mods available, but someone else would be better to ask about how good the AI can get.
There are also quite a few ongoing multiplayer game sessions of both games, as found (and managed) on the http://pbw.spaceempires.net