score:8
If you read the guidance, you will see that question 6.9 asks about "any criminal offence (including driving offences) in the UK or any other country, at any time?" while question 6.11 asks "Have you been subject to, or received, any other penalty by a court or the police; for example caution, discharge, fine or community sentence in the UK or any other country?"
It seems clear that the answer to at least one these must be yes, and there is no exclusion for common traffic offences (on the contrary, they are specifically included). It is either a criminal offence or a "other penalty" and must be disclosed on your application.
You don't know whether the UK authorities will be able to find out about this matter, but it's clear that they take even trivial omissions extremely seriously. Failure to disclose it will hurt your credibility and could lead not just to refusal now, but difficulty with future applications, even a 10-year ban for deception in the extreme case.
As you note, it is a common traffic offence and rather unlikely to be cause for refusal. Failure to disclose it, when the form clearly requests that you do so, is cause for much worse. I would disclose.