Sometimes even the entire word is pronounced differently: read/read
IMO this long/short vowel ambiguity is the #1 broken feature of English spelling, and could be reliably fixed by adopting an acute accent to mark long vowels (where a double letter isn't already doing the job). As in: I love to réad. Shé read all my books. I watched the gáme líve. Shé lives at hóme. Eurydicé had a fíníte supply of pátience. Etc. It wouldn't change any of the ASCII-only spelling rules, and would be a…
The fixed word-final E that marks "long vowels" has the special name "silent E". (If it's not word-final, it won't appear at all. Thus "mating" has a silent E overridden by the -ing that follows it, and in order to spell a "short A" in the same context you need to divorce it from the following syllable by doubling the syllable-final consonant: "matting".)
But you can't use this as a basis for English spelling reform, because - to choose only the most obvious problem - English uses a lot more than 10 vowels.
So, when you write réad, am I supposed to understand /ɹi.æd/, a two-syllable word with a long E followed by a short A? When you write "had a", am I supposed to understand that both words are pronounced with identical vowels? When you write "lives", am I supposed to understand that this is a two-syllable word in which the first syllable contains a short I and the second contains a short E?
What problem are you trying to solve? How would you spell "put"?