Don't ask for repairs, let the underwriter do it. With a photo they surely will have an opinion. Around here most homes only have 1 bath, this house now has 1.1 baths which is more than sufficient for any emergency visit, if full bath is in use. The bathroom is actually totally gone. If you don't want another bathroom then it's just cosmetic stuff. But either way, better to get the exact answer from the lender to avoid the stip to add it, or don't add it. I would have asked the owners if they had the money to finish it, which might determine my approach.
Contractors are the worst owners, i have seen them take months to finish stuff in their own homes.
GLA, not GLA, more ansi nonsense. Call it a rustic closet.