In your subject title you mentioned "hours / no-incident verification" and in the text above just "job verification". The two are not seen as the same in may places. I have recent first-hand experience trying to get a reference letter from a major UK airline confirming not only my dates of employment and job title but also my hours flown as per their records along with a "no-incident" verification. HR produced a very basic letter with the dates but refused to provide additional information. They also blocked the Pilot Manager from writing such a thing. Despite my plea that without this my employment chances abroad will be limited, they continued to refuse (The Arabs and Chinese demand this sort of thing all the time).
I highly doubt there's such a rule at the EASA level (EU forget it). In the UK, we have the following:
https://www.gov.uk/work-reference . It tells us employers don't have to provide one if they don't want to but must if they are in a "regulated" industry. And even then there's no rule specifying level of detail. Can "regulated" apply to aviation? Who knows...