Whilst a slightly different scenario, the following detail may be of interest / relevant:
In the example of a Cllr failing to accurately complete and declare ALL of the required fields in a declaration of interest (similarly - assumed to be a (strict liability) criminal offence by dint of the Statutory requirement) it was wholly anticipated that reporting this to the Monitoring officer would be a complete waste of time. In fact, it WAS a complete waste of time since the MO decision was, that since the omission had been corrected, it was not in the public interest to prosecute.
Anticipating that the MO would be a waste of time and effort, that scenario was reported direct to the police bypassing the MO.
The police then sought input from the MO (and don't forget - a LA is actually a prosecuting authority (like the post office (and the similarities are obvious!))
So whilst it may 'appear' that a potential criminal offence may have been committed by the candidate, you could report the situation to the ERO (many EROs are also the MO BTW) but I think we all know how nugatory that route can be, you could report it straight to the old bill, but they would likely seek the advice of the ERO/MO and probably pass it back to the LA for investigation / prosecution decision.
FWIW - I would submit direct to the police and let it take its course, at the very least that would ensure 'external agency' being aware of ERO/MO action / inaction.
As to what the outcome would be viz-a-viz the assumed electoral transgression - if there is no investigation / prosecution I suspect there would be no follow up action and this will be consigned to the ever growing file of MO irrelevance.