Steve,
It turns out that tDOM 0.9 also depends on TCL 8.6. Thus, I solved the problem, amending install-ns.sh script to install tdom 0.9, tcl 8.6, and of course NS 4.99.16.
Furthermore, upgrading TCL to 8.6 was an old task that I had postponed from a while ago, because of an issue that not only myself but also Michael Aram had. He's posted here in OACS Forum, regarding [ns_return 200 text/plain ${v}v]
i.e. "Ain’t No ☀shine", https://openacs.org/forums/message-view?message_id=5379887
@Gustaf, rl_json is just beautiful! Thanks for the tip Gustaf!
Best wishes