That's certainly true for things like vowels, but there are other situations where spelling could be changed with no ambiguity problems in any dialect. For exam

That's certainly true for things like vowels, but there are other situations where spelling could be changed with no ambiguity problems in any dialect. For example, basically every word that contains "gh" can be simplified, as <gh> represents a /x/ sound like German "Bach" that dropped out of the language in the 1200s. Nobody is confused by "tho" and "thru". Another easy example is just fixing "island". The <s> was never pronounced. Medieval scribes put it there because they incorrectly guessed that the word was related to Latin "insula".