Yeah no problem. Let me know if you have any issues with it or suggestions for things to add, even if its small little behaviors the original editor has that i forgot to include
One thing I noticed right away that might be worth looking into is that there is a difference in how your program creates outlines from how later iterations of GameMaker did it. The current behavior seems to mirror how it was in Game Maker 7.0, where it'd create extra pixels in the corners (something Pixel Artists refer to as "pixel imperfect"). This was changed in Game Maker 8.0 to a more desirable behavior giving outlines a smoother look.
I think having the ability to pick either would be massively appreciated. Another thing I'd love is for the interface to reflect the design of current GameMaker for the sake of cohesion, or at the very least offer a dark mode theme. Aside from that, great job 👍 the old sprite editor is my favorite pixel art tool ever and not having it kept me using GM:S 1.4 during the prototype phases of my games.