Eoh
editHello,
There are a few more ways of transliterating eoh; not just "eo". As the article you mentioned says, there's also "ï", and R. I. Page, who mostly dealt with English runes, transliterates it as "ɨ"; there might be more. In terms of where eoh is actually found in actual inscriptions, unfortunately, my memory fails me; I can only recall it being used for [ç], in the inscription raiɨan (my transliteration), but I think it's also used for a vowel somewhere near [i] (no idea where it'd be used for that). I do not remember finding any inscriptions that use it for /eo e:o/, and so I believe that those values only have to do with the manuscript mentioned in that section of the article on A-S runes. The reason the rune has such a variety of possible values is that the vowel it originally represented fell out of the language a long time ago; I believe Elder Antonsen in his Runes and Germanic Linguistics says that rune was probably redundant even for Proto-Germanic. I'm not exactly sure why the runemasters held onto it, but the fact that a rune is more than a symbol for representing a sound could have helped.
I've actually been meaning to improve this Wikipedia's articles on runes, but I never actually get to it. Maybe some day. Though, perhaps I'll get to doing proper work for this rune in a few weeks.
Please tell me what you think.