Hi, Meursault,
I was also not convinced by the final grid entry to 1dn, but there’s a German examination called the TestAS - Test fuer Auslaendische Studierende (sorry, can’t do the umlauts), so maybe this creeps in as a name. If we can have a French name as the grid entry for 26dn, why not the name of a German exam for 1dn?
For 16dn, I had no problem with “one” referring back to “engineer”, so that word serves as both part of the definition and the anagram indicator. Axed did a similar thing on Sunday with the clue “River, rapid roller near battlefield, one in spate”, where the definition is “one (I.e. river) in spate”, and “river” leads to the letter “r” in the wordplay. But perhaps this is more straightforward as “river” is a noun in both contexts.