I don't really get the complaints that The Sims 5 is copying Paralives. It's very possible that the developers are looking to Paralives as a source of inspiration yes, but frankly, push and pull mechanics for customization are increasingly common in games focused on customization, and it's really about time The Sims 5 has an in-game mesh manipulator of its own (Spore had a system like this all the way back for starters). Paralives didn't patent user friendly 3D manipulation tools, if the tool UI they developed is convenient, easy-to-understand, and is completely functional for the general player, why not take inspiration from it rather than attempting to reinvent the wheel.
In addition, the bare minimum UI that could also inspire the similarities between both games isn't a priority at this stage of development. What's important to the developers is that the game is functional first and foremost. Frankly, both Paralives and Project Rene has minimalist UI since both of them are very early in development because that type of polish and helping give your game an identity is the last thing that happens.
The Sims 4 engine is also ancient. Old. We're talking about "it used to support 32 bit systems" old. We could use a new game that runs on a more modern engine at this point, like support PBR shading in our models for one. In fact, one of the reasons Sims 4 has a messy code was because it was hastily screwed around with when SimCity launched as a disaster.
I don't think EA even views Paralives as a serious competition at all, and I don't think even seriously considered it when they released footage for Project Rene. It's not really in the public mind, while the Sims still practically prints money (evident by EA still supporting an 8 year old game when it could have pulled the plug on it if it didn't sell well).