Here's your answer, I guess:
"it's too much work to maintain ReaPlugs, especially given some of the newer more-advanced features, so we're deprecating them and they will likely not be updated."
https://askjf.com/index.php?q=5871s
Still, I'd like to at least see ReaJS updated considering the other ReaPlugs have many reasonable alternatives, but ReaJS is the only way to use JSFX outside of Reaper.