I'm not certain when it started with recent snaps but I believe it was AFTER** 19w03c because I was generating a lot of island seeds in that snap and never had the crash. Recently I noticed it starting with 19w06a. I've been looking for a good map to play with my nephews for the 1.14 release and experienced this crash even while far away from the ocean while underground in spectator mode (presumably generating underground water/lava).
Yes, indeed. I'm playing in survival and have about a dozen or so villagers with all trades locked. Some are still at the lowest tier while others are locked at the highest tier. Definitely some kind of bugged out mechanic because (at least while selling items) it seems whenever I get a new red 'X', the visual response time seems super quick, I get the emerald for whatever I traded, and the item count in the trade box resets to the pre-trade amount when I remove the unsold items (returning my sold items to me).
After reading online and watching some videos about the recent changes to bedrock, I'm starting think what we're seeing in these snapshots is a transitionary state towards new villager mechanics. Assuming of course that Mojang's intention is for approximately the same villager mechanics in java and bedrock (which does make sense to me.)