In the point-of-view culture in my story, all of the women in priestly families have two-syllable names beginning with vowels. (There are reasons for this, but they're completely tangential to my question.) I've gotten feedback from a beta reader that the character names look/sound too similar, even with my attempts to vary the specific vowels, the intermediary consonants, and terminal consonants if present. Examples: Elish, Ara, Efa, Eril, Aygo, Ina, Ilu. I'm guessing I should be using more "compound" sounds like "ch", "th", "br", etc.

I speculate that some phonemes are "more different" than others, and that I could make names more distinct from each other if I knew which those are. I also realize that some people "hear" names as they read and others don't, so it's possible that "hearers" perceive differences differently than "seers" do.

Within the constraints of the naming pattern in my world, how can I make characters' names look more distinct from each other?

In the point-of-view culture in my story, all of the women in priestly families have two-syllable names beginning with vowels. (There are reasons for this, but they're completely unrelated to my question.) I've gotten feedback from a beta reader that the character names look/sound too similar, even with my attempts to vary the specific vowels, the intermediary consonants, and terminal consonants if present. Examples: Elish, Ara, Efa, Eril, Aygo, Ina, Ilu. I'm guessing I should be using more "compound" sounds like "ch", "th", "br", etc.

I speculate that some phonemes are "more different" than others, and that I could make names more distinct from each other if I knew which those are. I also realize that some people "hear" names as they read and others don't, so it's possible that "hearers" perceive differences differently than "seers" do.

Within the constraints of the naming pattern in my world, how can I make characters' names look more distinct from each other?