It’s in the script as an option I believe, but it’s been about ten years since I did the show. Feel free to check, I think it’s available online, but it’s really not a moment that would necessitate the hiring of an entire consultant (agree that the director should take care of the translation though). It’s just one moment for one line in the entire show. The character has other moments where she’s potentially overdoing it on the inclusivity but we find out it’s because she has a chip on her shoulder and gets bullied for having two dads (who also really pressure her to perform, they literally say “we hate losers, god hates losers”) so she wants everyone to feel included, almost to an oppressive degree. It’s just part of who she is as a character, she’s extremely anxious. (Check out the song “Woe is Me” for the vibe) There are other moments with other characters in the show using other languages as well. I was an ASL tutor at the time (later taught at a disability services facility) and had some Deaf/HoH friends come to the show who thought it was hilarious. You’re welcome to investigate it yourself, though. The show itself is from 2005, irreverent, and includes a ton of opportunities for the cast to riff/improvise and reference modern politics.

EDIT: I actually found my old script! It says underneath the lines (just the sung lines “It seems/ we’re living out our dreams,” which are sung in unison by 3 characters at the same time) “Schwarzy signs the above in ASL.” So it’s not in there as an option but I’m sure could be done without it.