I had three computers, A, B, and X connected using Syncthing. X was an always-on desktop computer configured as the introducer.
X died. I may replace it, but in truth I don’t need to share many or any files with it. I configured it as introducer in order to share files among more computers which are no longer active.
If I remove X in Syncthing, will A and B still be synced? Or will I need to recreate the shared folders between those two devices?
Introducer is just a way to make all devices aware of each other for connection purposes. It is not needed for sharing.
Make sure that A and B are sharing with each other. Or to put it in another way: Under “Shared with” on A, make sure that B is mentioned. And vice versa. There is no need to recreate anything.