Redtail - while I understand you not wanting to drop a co worker in the **** - how will you feel if an aircraft signed off by one of them is involved in an incident resulting in loss of life?
You knew they were not up to the grade & said nothing! Will you be able to sleep at night?
With our AMELs & approvals comes responsibility, if someone is dangerous we can not sit back & ignore it. Quality issued the approvals, they should be a good place to start.
Maybe they can arrange refresher training or something but at least safety will come first.
The problems you have will become more & more widespread as the number of experienced engineers drops.