So I did some more poking, the code range is 0x0E000000-0x10000000, not 0x0E300000(so TCPGecko is wrong). Looks like the RPX (at least for Sploon) is loaded straight at 0x0E000000, it has like a nop and blr at 0x0 and the full code starts at 0x20, it just pads all that to zeroes so it's a 1-1 copy, and the dynamic loading section is directly after the code. All data is put in at 0x10000000 like you'd expect, if you wanna get an address probably just dump 0x10 to 0x20 and search for the actual string or a string next to it if you're looking for a vtable or something.
To put it in simple terms, if you're looking at the RPX in IDA, 0x02000000 = 0x0E000000, if you're looking for code. If you're looking for strings/data to edit, everything modified is in the 0x10 range, and I've only ever seen important stuff from 0x10 to 0x20, maybe 0x28, you want to try to replace the actual string in the code and make the game process it normally by getting it to reload, it'll do all the heavy lifting for you. Depends on the game, most Splatoon stuff just uses IDs and gets the right string based on a list ("cNone, cDay, cNight"), so I can swap them around to get where I'm not supposed to. I know the .bss section is also in the 0x10 range, haven't pinpointed exactly where it is.