The name yod-shin-mem-'ayin-alef-lamed  should be romanized Yishma'el (with diacritic for  the  'ayin only),
per HCM p. 12, namely, not Yishma<>el  with diacritics for  both  'ayin  and alef).  This is because initial  and final alefs are  not represented in romanization.  Medially, they are represented by  the alef diacritic only when the alef itself, not  the  letter  before  it,  is  punctuated  with  a  vowel  in Even-Shoshan's dictionary.  So,  adon (initial),  matsa  (final), matsata (medial), Yehezkel  (medial), Yishma'el (medial).