First of all: it took me a while to find where I can post ideas, with issue trackers on GitHub, GitLab, invent.kde.org, bugs.kde.org and discuss. I think, brainstorm is where you want it to happen, but glaxnimate is not in the tags to choose from. Sorry if I missed something Maybe you can put clear instructions into glaxnimate and possibly all these places to tell contributing users where to go for bugs, discussions and so on.
So, the question or idea is: onion skin for glaxnimate. It would support a more manual workflow where you reposition shapes based on former and later keyframes.
Thanks for your great work, I think glaxnimate fills an important niche of a simple and small animation tool and I am super happy to see it in KDE and integrated with kdenlive.