I was travelling through Vietnam and thought it funny just how many diacritic marks Vietnamese text makes, and thought that English was better because it doesn't need them. Then I realised that - holy shit! - English needs them big time. Look at wind (air movement) and wind (wrap around), or wound (injury) and wound (past tense wrap). Or even read (view text present tense) and read (view text past tense).

Admittedly I'm only a monoglot, but Engish seems pretty brutal in expecting you to figure out the correct sounds from the context. A few diacritics sprinkled in could likely really help newcomers with appropriate sounds.

On a tangent, one of the things I like about written Spanish is that you know at the beginning of a sentence whether it's a question or an exclamation. It's always a bit weird when reading a long sentence in a novel, to get to the end of it and think "oh, that was actually a question..."

I think the degree of fault tolerance depends on the age of the reader. My first computers used discrete transistors. My high school English teacher was a strict grammarian. I paid close attention because I was dating her daughter, also a strict grammarian. To this day the misuse of "to" for "too" will bring my brain to a full stop. I am moderately adapted to the confusion of "fewer" vs "less". (It's countable vs uncountable.) And I even use "they" as a gender neutral third person singular, but you should never do it in formal writing.

I read an article sometime in the past year that maintained that all the prissy rules were imposed on a perfectly good language by self-imposed arbiters of the language. Sorry, I cant locate it at the moment.