I think you’re overthinking it, Nev. When Leia sends her assistant-person to the Republic to “insist they take action against the First Order,” all the Resistance knows is that the FO just attacked a seedy bar. That’s certainly enough to make Leia worried, but do they have any tangible proof about Starkiller Base yet? Heck, they don’t seem to have any data on it at all until 10 minutes before the battle, when Poe does the whole “This was the Death Star. This is Death Star 3.0” thing. The fact that assistant-person is still there when the system is destroyed makes me think the Senate is still stalled on the matter.

Starkiller’s been built in secret, and the Republic doesn’t really seem concerned with the First Order as an organization. I don’t think it will break the suspension of disbelief if the Republic’s not actively fighting the First Order. (That’s kind of the point of the Resistance, no?)