Hi CaptainBlueSky,
Thank you for sharing your feedback based on your gameplay experience with Stranded Deep - I’m glad to hear you enjoy the game too! I shall pass your feedback onto the team and I will keep an eye on this thread as I’d be interested to hear if other players have experienced a change in building limitations similar to what you’ve mentioned above.
With regards to animals respawning on custom islands, this was added in Patch 6 but appears to have an issue at the moment, I have a report for the team filed on it and have noted your experience in the report also.
And while I know the workarounds are not ideal, there are some for placing things inside buildings in this topic - [Known Issue] Difficulty placing crafting stations inside buildings - You may have already seen / tried them before, but if not I hope they’re of some help.