But Larian has a way to do things...their way, and I doubt (hope im wrong...) that they would emulate a similar system from another game maker.
I'm not disagreeing, but I'm just going to put it out there - if they aren't prepared to put their own way of doing things on hold, and instead emulate a different system, then they should never have agreed to make a 5e dungeons and dragons game, nor advertised to their fans that that was what they were making. Because that's a different system to their style, entirely, and having taken on a commitment to make that, and having advertised their intention to do so publicly, they now have a duty to deliver it... A duty which they are not meeting as of yet.
The other game would not be something that they would be copying, in this sense - its existence just highlights how badly they are not adhering to their own undertaking and what they advertised to sell copies, at the moment. The other game has a faithful 5e implementation of reactions. Asking for BG3 to faithfully implement reactions and their function as well is not asking them to copy that game, it's just asking them to do as they themselves said they were going to; the other game is just demonstration that this works and works well, and doesn't need to be tinkered with.