Hey Loart! Thanks for sharing the screenshot, that really helps clarify things.
I think the confusion might be in how the pack is intended to be used — these assets are designed to be used individually, not as a traditional tilesheet. Each sprite comes with a transparent background and is organized by category, so the workflow is to place each asset one by one rather than slicing a grid.
Because of that, trying to grid-slice the sheet in Aseprite will cause exactly what you're seeing, since the spacing isn't uniform — it was never meant to be sliced that way.
The correct workflow would be:
• Open each individual asset (or category folder) directly
• Import them as separate sprites in your engine or editor
• Place and arrange them manually in Tiled or Unity
This gives you a lot more flexibility since you're not locked into a fixed grid!
That said, if this workflow doesn't fit your project's needs, I'm totally happy to help you with a refund. Just let me know!