Rimevel

Anyone with good knowledge about rendering fluids inside a custom model? The model should also reflect the level of fluids of the tile entity. I have been looking around for a way to do it and experimented a fair bit myself but I can't get a good result

How will this update affect "coremods"? Will it still be possible to replace vanilla items/blocks, alter game settings directly etc? I'm currently doing this in my survival mod to change some of the core gameplay of the game. Ofc without directly altering any Minecraft classes directly. I guess I'm just a bit anxious about the update