Well I'm using Linux and the longest I'm seeing so far is something like:
/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Metadata/TV Shows/1/2adcc482210339c41fd958667dc685cdabd0a80.bundle/Contents/_combined/seasons/2/episodes/24/thumbs/com.plexapp.agents.thetvdb_8e7bca176cc9630fe8661ac4336f81b39c4cdd98
This is 253 characters so it's getting pretty close. I guess none go over?
Although searching around I'm not finding anything about max path length on rsync (just max filename length) for Linux, just Windows seems to talk about max path length.