TeXmacs uses "maxima --list-avail" to list available Maxima version and the first line of this list is shown as "default" in menu which is not correct.  Actually the versions order in the --list-avail output is more or less random.  Maybe this is Maxima fault but I venture to suggest a workaround.  Let's just show all menu items as it is with explicit lisp type  indication. One can also add special "default" menu item which should start bare "maxima" command without -l option.
So if for example we have two flawors of Maxima installed, say gcl and clisp, then we shoul have three menu items:
1) default  - "maxima" command
2) maxima clisp - "maxima -l clisp" command
3) maxima gcl - "maxima -l gcl" command