I'm sorry, saying "have a great party" == "coming on too strong"? Look, I get it, you're 100% positive for this game, I love the game too, but come on, let's talk about real people for a minute. If I said to someone at a gathering, "Hey have a great night, take it easy", NO ONE would take that as "oh my..they were hitting on me" or any sort of meaning where a "Sorry, I came on too strong last night".
Definitely just saying "have a great night" wouldn't be coming on too strong, but in my case I think I'd tried using a charisma check on Halsin, so it wasn't just that. And if a friend had said they didn't want to go to a party and, rather than taking them at their word, I'd tried to twist their arm, then absolutely I'd perhaps feel afterwards that I'd come over too strong (not in a flirty way, but in an overly pushy way and not respecting their choice).
But I think the different possible meanings of "coming on/over strong" are moot, in any case, as I went back and reloaded to try the dialogue option and it does look as though the game probably means it in the context of having been flirty ... maybe? Even if so, I personally don't see this as hugely problematic, given that if that's not the way it was intended then I can just not select the dialogue option (it seems to vanish later once Halsin's quest moves on) but ideally it wouldn't be ambiguous or raise the concern that the game thought I'd already done something I didn't intend to do and that I ought to apologise for, rather than it just giving me an opportunity to confirm how I did or didn't mean what I'd said. I've put a screenshot of how the conversation panned out below for anyone interested, and in case anyone does think it's severe enough to warrant a bug report:
"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"