Is it in poor taste to ask a semi- personal friend if you are still on for a fundraiser she invited you and your husband to?

Yes. Just as casually as you posted.

Since you received an original invite, of sorts, it doesn’t seem like it should be a problem to give her a courtesy call and confirm. If you felt uncomfortable, somewhat, you could maybe disguise your doubt by asking something like what you should wear or getting directions to the fundraising dinner. If there was any changes to the original plans, it would then be your semi-personal friend’s responsibility to take it from there and do the rest of the explaining.

I agree with @Dog .. your post was perfect. Ask it just like that: “Are we still on…”

Not in poor taste at all! I’d just give her a call to confirm.

Absolutely, since you will have to pony up for your portion of the table cost, it would only be fair to find out if you need to write the check to her, or to the charity. Hopefully to the charity so you get your portion of the tax deductibility of the tickets.

Yes, your course of action seems completely appropriate here.

I wonder why you feel hesitant. Seems like just the right thing to do.

Call her!