A couple of things that may help
The WMO technical regulations only hold two types of requirements
Mandatory and these use the word Shall. Members shall .....
Recommended practise and these use the word Should. Members should ....
Theoretically regulations written using should are expected to be changed to shall at some stage in the future.
So if the Tech Regs hold a competency framework, then already in your words they are nearly mandatory if they are a Recommended Practise. You would be expected to have a good reason to have not implemented them. All competency frameworks with the exception of the one for aeronautical met are Recommended Practises. Partly this is practical as there is no international regulator with national representation in the climate, marine, public weather services ... areas.
Congress is the body that sets / agrees the standards. As Congress only meets once every four years they have delegated authority to Executive Council who meet on an annual basis to approve changes to the tech regs that cannot wait until the next Congress. There is also an procedure to allow updating of the Tech regs between ECs and this is usually for communication codes or similar that are operationally important and timebound.
So the Secretariat do not create the technical regulations, they assist in preparing them for discussion in the technical commission expert teams and sessions and then later for EC / Cg. The Secretariat are then charged with publishing them.
In most cases, but not all the technical regulations (there are four volumes) are created by the technical commissions and following discussion and resolution presented to the WMO Executive Council for approval for inclusion into the Tech Regs. For ETR and thus the trainer competencies, EC itself was the instigator (through the EC Panel on ETR) as well as the approver.
I suggest you have a talk with Ian Lisk who is very au fait with the Tech Regs. In the end if you are still unhappy with this situation, raise it with your PR as he is an EC Member and if you can convince him then he can raise the issue for discussion in a range of venues. In the mean time it is sometime best to just say, this is silly but I personnally cant change it right now so lets work with the current obsolete or what ever system we have to use.