How useful is this decompiled source code? I had a look and most of the code looks like this:

bool fn_80173510(void) { u16* temp_r31 = gmMainLib_8015EDA4(); bool var_r30 = true; int i;

    if (gmMainLib_8015EDC8()->x5 == 0) {
        for (i = 0; i < 11; i++) {
            if (i != 6 && i != 7 && i != 8 && i != 9 && i != 10 &&
                !(*temp_r31 & (1LL << i)))
            {
                var_r30 = false;
                break;
            }
        }
        if (var_r30 != 0) {
            gmMainLib_8015EDC8()->x5 = true;
        }
    }
    return gmMainLib_8015EDC8()->x5;
}

My understanding is that the source code itself is not the "goal" as much as a way to recompile the game for other architectures instead of having to use emulation to play the game. Also for modders who want to alter things at a low level (performantly).

Over time, as needed and where it makes the most sense, I could imagine that _rough_ source being cleaned up (same logic, but real names/comments added) so that it's easier to follow.

Getting code to re-compile byte-for-byte into the original game is the first step to being able to clean up that code to be human-readable.