I think that even that is too limited. The whole audible system on defense should be overhauled.
1. Have multiple layers to audible - check to a coverage. If it's a split field coverage, have a "BASE", but be able to adjust strongside/weakside based on the situation (MOD/MIX/SWITCH/BRACKET, etc.) Weakside (MEG, DOG, CONE, CONNIE, CUT, POACH).
2. The ability to customize the available audibles for certain situations/alignments (want different audibles to appear for trips? Select STUBBIE/SPECIAL, STUMP/STOMP, SOLO/POACH, MABLE/SKATE, etc. What about how to play against a bunch formation? BOX, BINGO, NAIL, etc.). Or even by specific formation, like a reduced weakside split, check to something like 2 CORA.
3. Custom play design in general. This could be locked down or limited to a point where it couldn't really be exploited (so long as they bothered to test it). Want to come up with your own coverage variation of quarters? Go ahead. You would only need to build in a very FINITE list of match principles based on position (Example 1: MEG. Example 2: Primary - MEG #2 OUT/VERTICAL, ELSE MEG #1, etc.). It would require very simple boolean logic combined with known zone and route classifications. You could even prioritize the run by having a "RUN FIRST/Read MESH" Option (i.e. if there is play action, play the run) like there is in MIX.
4. I get really mad at the run fit options as well. I think you should be able to make more robust defensive line adjustments to set a D-lineman to play either a 2-gap or 1-gap technique (example: Alabama JIMMY/PONY Call). It's so difficult to play linebacker because you have no idea wtf your defensive line is going to do, and you're almost always wrong even with the run fit play art. You should be able to make more fine adjustments to the run fit, and even customize it by your defensive alignment and/or the offensive formation.
This should ALL be available in the scheme settings so you don't have to do everything on the fly in the game.