There is no "installing", it's just replace & run -- and there is no aspect ratio distortion, unless something somehow went wrong on your end that shouldn't have been possible to go wrong.
Most likely you're simply referring to the typical character design for DQ that's extremely similar to Blue Dragon as well as Dragon Ball, since all of those had the same lead character artist, Toriyama-san.
If it looks like this on your end, everything's fine... if it is wider than that (relative width, mind, not absolute), then yes, something isn't working as intended.
Also, as one can see from my screenshot, I've gone back to the original .exe -- those glitches with the fade outs are just so majorly ugly and annoying, I'd rather play with bars than endure 100+ hours of those visual glitches.
Still thankful to everyone who tried making 21:9 true Ultrawide possible, of course, just angry that Squenix has screwed this up so badly and made it so hard to fix.