Band a lot,
Fitting Standard AA Batteries in an ELT poses no problem, because that's what you're told to do by the approved maintenance/overhaul data.
Similarly with most megaphones fitted to Boeing A/C:-
"The power supply used in the megaphone consists of six standard 1˝ volt
“AA” size batteries"
However, and I'd like to start by saying my experience lies firmly in maintenance of Boeing A/C, I'm fairly sure in the Airbus AIPC it will give an exact part number of bolt to be fitted (down to the exact length).
Approval could possibly be granted to use equivalent parts, however these equivalent parts would have to be made form the same material, be heat treated to the same hardness and have the same coatings as the original.
Equivalent parts also normally need to be identified as such.
And the chance of finding a titanium with a cadmium coating down at Home Depot is probably pretty thin.