Request Abou Sims3

@Akihra  As far as EA is concerned, there hasn't been a development team for TS3 in years, and the last meaningful game update was (I think) in 2014.  So the chances of any more official improvements to the game are slim to none.  I have to say, though, in my very subjective opinion, TS3 was just as buggy before TS4 was released as it is now.  The main difference is that with so all the available packs, there are more opportunities for things to go wrong than there were with just the base game.  EA never put the necessary effort into troubleshooting TS3, so players had to do it for themselves, with varying degrees of success.

Speaking of which, while the out-of-the-box version of Isla Paradiso is so glitchy as to be almost unplayable, a couple of talented world builders have edited it and posted their work for others to share.  If you wished, you could play a fixed version of IP that works as well as, if not better than, any EA-made world.  Here's a thread on the subject:

https://forums.thesims.com/en_US/discussion/811253/removing-ip-lag/p1

It should also be noted that the gameplay features that come with the Island Paradise EP work just fine.  You can place the relevant lots and spawners in any EA- or player-made world that you like, provided that the water is deep enough for scuba diving and navigating boats.

As far as the other glitches you've encountered, you could always post on the Sims 3 forums (as in the link above) and ask what other players do to manage them.  There are still quite a few people over there, most of whom are happy to offer advice.  All you have to do is ask.