OK, thanks for your help!
Deletion from NAS #recycle even if in a Team Folder seems to only affect restoration outside of Synology Drive's scope.
Similarly, deletion from a connected Linux machine's TRASH folder only affects that machine's ability to restore/undelete (e.g., with CTL-Z).
IOW, #recycle on NAS and trash on client computers behave as expected and don't affect the Synology drive application directly.