worry about this "The latest Parenscript release, version 2.7.1, came out on December 5, 2018 "
Don't worry if a lisp project hasn't been touched for years. Worry if a project has a boatload of open/known bugs AND hasn't been touched for years.
How much has JavaScript changed since the last update of ParenScript? How many new language features, that might add real benefit, are not accounted for?
Maybe the answer is that the new features are unnecessary to parenscript, I genuinely don't know, but it would be nice to at least see discussion/acknowledgment of this featured somewhere prominently.