Well, a small update about this. The good news is I've come to understand something else about the changes I'm making, more importantly about one of the alphabets Capcom included in the game. Specifically, the "MISSION CLEAR" one, which is composed of 4 tiles per letter. At first I was having issues regarding the "CLEAR" part, as anything beyond that would get cut off even when there was enough room. Turns out that, much like SCORE and LEVEL, it's preceeded by a handful of bytes that dicatate several things, one of which is to extend just how far text can be printed on-screen. As you can see below:

I can now manipulate it to extend beyond the previous limit. Not by much, but quite enough. Of course, now comes the bad news - surprisingly, it's still related to the previous problem I had with SCORE. Turns out that I completely missed something regarding it. Simply repointing the thing isn't quite enough because it produced two bad results. I can't believe it took me a while to notice the first, but here it is:

First pic is taken from the original, second from a backup where I've been experimenting. Notice the difference (other than the insane amount of money, sorry, I was testing)? That's right, the $ is missing. Because there is no longer an instruction to print that out (as I repointed the start of the word, but not the remaining values) it doesn't get shown. The second issue - not in the pictures - is that when you lose and the pilot's image fades away, it now also carries garbled tiles after the image is gone. This is probably due to the SCORE repointing as well, since it kind of overlaps over the pilot's picture (as in, PONTOS ---> PICTURE ---> NIVEL).
To add insult to injury, there's not a lot of room to repoint things. I even had to backtrack to a previous version today because of this. Since "MISSION" isn't terribly different from "MISSÃO", I just rewrote the original, but had to repoint "CLEAR" as it was bigger. And since it requires two lines (two + two tiles per line), it took away almost all the free room I had. In fact, the only room I had was to place it right below PONTOS, meaning all three lines I had are now gone, and repointing these to anywhere else seems to be a no go (I assume it requires the info to be on the same offset bank).
The only thing I can think of at this point is to do with SCORE what Capcom did for weapon names - that is, group letters closer in order to maintain legibility but use less space.