Yeah, the fuse option local totally fixes it but you do need to run cache-mode writes as well:
textere@seraph bin % sudo ./rclone cmount gcrypt: /Volumes/Test --allow-other -o local
2019/11/23 11:48:49 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/0.indexIds: WriteFileHandle: Truncate: Can't change size without --vfs-cache-mode >= writes
2019/11/23 11:49:04 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/psid.db: WriteFileHandle.Write: can't seek in file without --vfs-cache-mode >= writes
2019/11/23 11:49:10 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/indexState: WriteFileHandle: Can't open for write without O_TRUNC on existing file without --vfs-cache-mode >= writes
2019/11/23 11:49:10 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/psid.db: WriteFileHandle: Can't open for write without O_TRUNC on existing file without --vfs-cache-mode >= writes
2019/11/23 11:49:10 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/psid.db: WriteFileHandle: Can't open for write without O_TRUNC on existing file without --vfs-cache-mode >= writes
2019/11/23 11:49:10 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/0.indexIds: WriteFileHandle: Truncate: Can't change size without --vfs-cache-mode >= writes
2019/11/23 11:49:16 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/psid.db: WriteFileHandle: Can't open for write without O_TRUNC on existing file without --vfs-cache-mode >= writes
2019/11/23 11:49:16 ERROR : .Spotlight-V100/Store-V2/4DD496ED-DF24-43E7-8E02-F1027EA2DCAB/psid.db: WriteFileHandle: Can't open for write without O_TRUNC on existing file without --vfs-cache-mode >= writes
Is what I see when I check the mount:
gcrypt: on /Volumes/Test (osxfuse, local, synchronous)