I would like to have different macros depending on the original source setting, I think this may be possible using the .A modifier etc. when the extmute_on happens, but i don't think it would work on the extmute_off event.

Sheesh, the IR hackers here have forgotten all the tricks since they got their own setups working a couple of years back!!

Here's how to go about it in this case:

The extmute_on/extmute_off codes can be just about any codes you want them to be, with a few restrictions only on the highest order 4 bits or so. This means you can do this:
[hijack]

extmute_on=0x1234
extmust_off=0x5678
Now, of course those two codes by themselves don't mean anything to the player software. But.. you can now define meanings for them, in terms of Hijack IR-translation macros. For example:
[ir_translate]

0x1234.M=Auxiliary
0x1234.T=Auxiliary.S
0x5678.S=Player
0x5678=Tuner
Or something like that. Hopefully you can figure the rest out by experimentation, and maybe.. just maybe, some of the original IR -translate users here will jog their memories now and add some ideas.

Cheers