Thank you for raising this subject. Perhaps this would be worthy of a more formal consultation? Our view is that badge and certificate are good but perhaps not used to their potential.
As David says it's good that "the person will receive something for taking part". This should be the badge not the certificate. As the OP said, the certificate could be a useful measure of progress against each outcome. This would make the most of the excellent strength of Bikeability in moving away from the woeful days of "pass/fail". For example, the parent/carer of a child trainee might see they need to focus further help on the right turn out (or whatever). The Bikeability certificate could really contribute more to the idea of progression and continuous self-improvement and thereby cycling regularly.
A few years ago we had an adapted version of the certificate that detailed how the trainee did against each outcome . As part of this, we asked some parents/carers what they thought and they preferred that detail. Whilst the new certificate does state, 'has taken part in' it also says, 'At Bikeability Level X you can:'. I would guess most people would interpret the latter as a pass.