I’ve used ResilioSync for years to sync folders between my iMac and MacBook Pro. It also syncs to my server Mac so that the iMac and MacBook Pro do not have to both be on for syncing to occur. It has an advantage over Chronosync in that the syncing is continuous and works even if the systems aren’t on the same LAN.
My understanding is that collision detection is a problem with MacOS because it wasn’t designed to handle shared data resources. Applications must set up their own protection scheme (usually semaphores) to avoid collisions. Since I don’t use both computers simultaneously, this isn’t an issue for most things, however my wife and I do share a Quicken database and this was an issue until Quicken addressed it a few years ago.