I think the only major hardware issue I've heard attributed to RoHS was some of the errors with xbox 360s because microsoft weren't great at using lead free solder yet. Though, I didn't go looking.
There were a bunch of mostly small-scale issues with solder whiskering, yeah; that Xbox thing was probably about the biggest. Swatch also notably had major problems (though they were trying to eliminate leaded solder somewhat _before_ RoHS; it's not like no-one cared about this until RoHS).
Also, of course, "systemic problem with _leaded_ soldering" was also a thing before RoHS; it's not like all was well in electronics manufacturing before then. You may, for instance, if you're old enough, remember the circa 2007 MBPs with the dying GPUs; that was a solder thing, and it predates RoHS.
