If you are worried you may need to check both the stud and the case and the above gauges would be useful as they are go/no-go type.
IMHO typical fit for a stud of this type would be 6g/6H and this would be OK for use with a thread locker.
This means an external thread with a tolerance of Class 6 and position 'g' with an internal thread with a tolerance of Class 6 and a position of H.
This is an ISO designation but is roughly equivalent to 2A/2B and is a reasonable average fit.
I would say that a good thread chaser shouldn't cause any real issues and we have used chasers for some time.
We do have a thread plug gauge and always check cases just for peace of mind and they are normally OK after this type of treatment.
I am not sure I would like to see the fit much worse than this although there is a small amount of leeway It all depends on where the lack of precision occurs.
If the fit is poor and it is the studs then they can be replaced with a more accurate part.
If the thread chasing has caused a problem with the case threads then you could fit timeserts.