Celtics
Celtics are limited on future 2nd rounders they have to trade or use. One of the 2nd rounders would likely have some protections for the Jazz. It's a minor move that opens up more time for Pritchard and helps the C's move to get under the tax.
Jazz
Jazz get a very solid back-up PG, albeit he will likely be a rental. This is in attempts to help push them toward contention this year. Jazz use their TPE and don't need to send any salaries out.
Overall
I wonder if the C's would benefit more in a Schroder deal if they got a player back. It's just hard to gauge his value because he's likely a rental for anyone that acquires him. I think if the C's can come away with 2 unprotected 2nd rounders or 1 unprotected 2nd rounder and 1 lightly protected one. Idk if the Jazz want to give that much though.