Most of the seventy-two follow one shape: three consonants, then a suffix. The sixty-second, usually printed Iah-Hel or Iahhel, does not obviously conform, and its printed form has attracted more comment than most.
The difficulty is partly typographic. The hyphen is an editorial insertion with no counterpart in Hebrew, and it makes the name look like a compound of two divine elements, Yah and El, rather than a root plus suffix. Different sources print it differently, and some drop the hyphen entirely.
It is partly a matter of the consonants themselves. Where a derived root already contains letters that resemble a theophoric element, the addition of a suffix produces a name that appears to double up, and the eye reads it as two names joined rather than as the output of the standard procedure.
And it is partly the accumulated effect of transmission. The name has passed through Hebrew, Latin, French and English, and each stage has made its own decisions about aspirates, doubled letters and word division.
The general point this illustrates is worth more than the particular case. The seventy-two look uniform in a printed table, seventy-two tidy names in a column, and they are less uniform than they look. Some are ordinary Hebrew names that already existed. Some are pronounceable but unattested. Some are awkward, and the awkwardness is what one would expect from a mechanical procedure that takes whatever three letters fall next.
That the list contains awkward members is, again, evidence that it was derived rather than composed. A list of invented angel names would be euphonious throughout.