I have repaired enough Iskras to know better than to buy one "remotely". Plenty of issues with those, nasty repairmen not doing a good job, and the camera itself is made out of materials with far lower quality than those from the Super Isolette. The Iskra goes for about 1/4 of the price that a good Super Isolette commands, and there are a few good reasons for it.
I cannot see how changing the flash sync setting may affect the winding (an independent, not linked system) or even the shutter once cocked, it is just a lever that moves and contacts (unless there are other underlying issues, something I wouldn't be surprised of)
That aside, it is not a bad camera when in working condition. The FXCh-18 shutter is a clone of the Synchro-Compur MXV, and the Industar 58 is a 4-element design.