It appears that domain words added to the Azure phrase lists are being used by Azure, but not as consistently as we would wish:
If the mathematical term "clopen" is added to the phrase list, it will be transcribed as "clopin" in sentences such as "the set is clopen", "a clopen set"
If the C function "malloc" is added to the phrase list, it will be consistently recognized in sentences such as "My favorite function is malloc". However, in sentences like "our program mallocs 12 bytes of memory" where it is used as a verb, it is rarely recognized correctly (It will most often be recognized as "Malik" or "my lock" instead)
It appears that domain words added to the Azure phrase lists are being used by Azure, but not as consistently as we would wish: