I don't know how to solve your issue itself, but perhaps you could work around it easily by opening a foreign file browser program such as Xfce's Thunar from within TDE whenever you want to get a different default file opening behavior. That way you won't have to work within Konquerer's design quirks.
I haven't tested that approach yet myself, but it seems like it may work, unless TDE overrides the default file opening behavior of the foreign file explorer program.
There is also of course the option of opening files via `open` from a shell instead of Konquerer, or opening the program you want to use first and then using it to browse to and open the file you want (perhaps with the file path copied from Konquerer in advance to find it faster).
Or, perhaps even easier, simply figure out the command names of the programs you want, then select the file you want to open in Konquerer, then press Ctrl E to bring up the prompt (which will already contain the file name, if you selected it prior to pressing Ctrl E), and then simply prefix that relative file name with the command for the program you want to run.
Oh, or perhaps even better, you could add a shell script to `/usr/local/bin/` which examines the file it is given as an argument and then chooses from your own list of manually constructed programs to run, so that you don't have to memorize the command names of the programs you use, unlike you would in the above workaround. You'd just use that custom shell command within the Ctrl E popup instead of a different command per file type. That could be a great middle-ground solution.
As the most "extreme" solution: You could even program you own simple file browser conceivably, which you could design to have use exactly the programs you want, which could add some flexibility but could be a lot more work potentially. If you kept it simple enough it may not be too much work though, and would be much more customizable in principle.
Anyway, hope that helps and have a great day/night!