What if ESR did these things:
Read SYSTEM.CNF on disc before booting it, and strncmp bootfile (i.e. SLUS_200.01). If it matches then you already know what settings should apply (spoof media in this case since it is Tekken Tag Tournament USA). Additionally, If you have some game known to only work with the direct_off version or direct version, you can also detect and set this.
We have compatibility lists and redump to figure out what to apply based on boot file. I really would like to be able to put any ESR compatibile game in my SCPH-10000 and have it just auto-boot from whatever soft-mod hook to call ESR. I don't really want the GUI, and it can be obsoleted in theory with the above ideas... I would try to do this myself but I don't think anyone else could compile a new ESR? Even if the source is messy I'd be interested in doing this if it is available in any capacity.
Edit:
I guess I could do this without compiling a new ESR. A new elf file could do the detection and then execute a specified ESR elf file (how do I specify spoof media in this case?). But making it a part of ESR would be the goal. Taking it as far as it can go as an idea.