but if a central database on these things lacks then it's down to you if you declare it or not, I wouldn't.
I agree that it's not a conviction but sometimes they do specifically ask about the course.
Are you 100% sure that they don't currently record this anywhere and insurers can definitely not find about it?
Suppose someone follows your advice or they decide to start recording this and you turn out to be wrong? If people lie then they can have claims refused and in some cases be pursued personally for 5 and 6 figure sums.

I would tell the truth with the exception of any questions I knew to be illegal (I agree with you that companies are not always right).

I accept you right to hold a different opinion but I think it's worth discussing the issue so at least people might think about the consequences.