I assume (but haven't actually checked) that altiereslima provided png sprites for their skill panels. Then they can be used in the new-formats version without any changes:
- For usage in packs, load them via the pack editor (tab "sprites").
- If you want to have them in all levels (even when playing single ones), then replace the corresponding files in "styles/default/panel" with the new sprites. For this they have to be named exactly as the existing ones. But if you do that, please don't make me responsible for any bugs that might appear due to such changes.

PS: I split the original topic and turned this into its own thread to be found more easily.