Official GBA games use up to 32KB SRAM.
As far as I'm aware, the Supercard doesn't have any mechanism to switch SRAM banks. Some flashcarts like EZ Flash IV do, by poking a particular MMIO register. Other cars like Everdrive emulate EEPROM & Flash commands for games which use those chips, so...
The size of the chip doesn't matter. SRAM addressing is restricted 16 bits (64KB) as a hardware limitation. You need banking to have more SRAM capacity, but as far as I can tell there's no registers mapped for this purpose.
Not having any of the carts which have been bricked, I don't know what the issue with flashing is. It seems easy enough, but I guess in practice it turns out a little different. Clones are definitely using new flash ids these days, because they aren't being recognised by the OFW installer...
A lot of people seem to be having issues with flashing the firmware lately, so maybe avoid this until I can figure out what's going on, or unless you have another way to unbrick it. The downside is, you can't use SDHC...
So, I took a look at the new Supercard which gives the "flash id cb2a" error.
It looks like this is already completely compatible with the existing flashing code, and is even recognised as a compatible chip by SCFW already. Only the original firmware does not recognise this chip.
Since...
It's probably a save banking problem. Pokemon GBA games use a special method to access more save memory than usual. Vanilla Pokemon games use this to save backup copies of the save file, so saving multiple times can ensure that at least one copy is saved correctly. Unbound is known to remove the...
Just checked a spare Supercard I own which I bought about 2 weeks ago which also has flash id c2ba. Looks like these are becoming more common in the wild.
I don't know yet why that happens for you.
And that's unlikely. The flash chip only stores the firmware data, and using a different flash chip should only matter while trying to install the firmware.