Replying to apnadkarni's 2025-07-25 18:00:57 comment:

After installing tcl 8.6.16, I did not try running the installed tclsh 8.6.16. Instead, I did:
% cd
% ./configure --enable-framework --enable-aqua
% make -j8
% sudo make install

That was when I got the message "application-specific initialization failed..." (as I described in the Description).