Thank you for the question about using UEB to transcribe an angle sign.
The angle symbol from UEB for Technical Material (section 11, beginning on page 50 of the Guidelines for Technical Material) is a "miscellaneous symbol" and not a shape, so it does not have a terminator that can be used with it. The next consideration is: Do we need a grade 1 indicator of some kind? Since the UEB angle symbol (⠸⠪) does not have a grade 2 meaning, it does not need a grade 1 indicator before it.
Thus, we can conclude that the appropriate transcription for ∠ZAX is ⠸⠪⠠⠠⠵⠁⠭
See also the self-directed "UEB TECHNICAL" course from CNIB (especially #5 on pages 17 and 18 for a sample transcription of an angle symbol unspaced from the angle's name).