The Windows Recycle Bin is very limited in functionality compared to regular folders.
It doesn’t retain the folder structure if you move items out of it to another place, meaning potential for clashes with items of same name.
It doesn’t provide facility to preview files such as images.
I therefore suggest you offer an additional, alternative option for InSync to move files to instead of trash, to overcome the above issues.
This alternative option, being a regular folder, would not have the limitations of the Recycle Bin and therefore enable comparison tools to compare it with some where else e.g. using Beyond Compare and MindGems FDFF Fast Duplicate File Finder (no afflilation) to check that the files are duplicate and can indeed be deleted.
I find that after reorganising my folders within InSync or unsyncing files locally, the Recycling Bin can build up with files and I find this daunting to be really sure that they aren’t needed or not, so the above suggestion would make this easier to determine.