So i have at least 3 devices, two untrusted. T is trusted, U I untrusted. T Syncs updates to U, but I is offline at this time. Afterwards, I comes online but T is offline now. Is I now updated? If i have a fourth device connected, (with correct password and all) will it be the same as the trusted device, even if they were never online at the same time, even if U was never online at the same time: tl;dr: the fourth only can connect to I
Welcome here @OWL4C !
Yes.
In a group of devices, the most recent edit/delete/create of every file will propagate to all other connected devices. Devices can come and go, in any order, and the latest state of every file will eventually propagate to all devices. This works regardless if some are untrusted and regardless of topology.
Kind regards /Martin