Nice👍
I haven't done animations in a long-time (since 2016 I think, but I never found it an easy task even when I use to make small flash games and other junk).
As for the layout.. it depends, some people prefer a grid type grouping of animations (might be easier for users of Game maker) or some do each animation set as a different image file or some prefer them just labeled and in a list type style. However it's up to you how you layout your work ☺️, we can re-center it if needed in most programs but most people prefer .PNG file type as it allows easy import on most programs and also allows for easy layering and transparency etc.
Keep up the good work!