The usual argument against spelling reform is that it isn't possible to do it in a way that is compatible with the language of more than one region. For example, in Australian English they have a system of phonemic vowel length. This does not exist in other varieties of English, so the options you have in a spelling reform are (1) ignore the Australians and set spellings that are ambiguous in Australia, or (2) placate the Australians and include their vowels in the reformed spelling system, despite the fact that this leaves everyone else in the world mystified as to why certain words are spelled with doubled vowels and certain words aren't.
Start small, and use compromises. Don't try to be completely phonetic, which won't work for the reasons you mentioned.
You can start by undoing misguided spelling reforms of the past. "Debt" used to be spelled "det" but due to incorrectly inferred etymology it was changed to be non-phonetic. There are many words like these.
Then look for major inconsistencies where a cluster of letters is pronounced more than one way, and simplify one of them. For example, "ough" is pronounced as in "tough" more often than as in "though". Change "tough" to be spelled as "tuff" and "rough" as "ruff".
Going further, embrace text/informal writing and use tho, altho, nite, tonite, etc. Although the last two are not necessary since "ight" is pretty consistent. Keep common clusters of letters so that it still looks like English. Do it in in stages over a 100 years , making changes every 15 years or so. I'm mostly aiming at ease of reading vs ease of writing.
Every other major language had a recognized central authority to do its work. Spanish, French, written Chinese, etc. all had a monarchy/dictatorship of some sort to mandate the change and enforce its use.
England could have done it perhaps in Shakespeare's time or shortly thereafter, but once English spread across the globe in its modern (lack of) form with no recognized central authority with the power to force the change, it's not going to happen.
You couldn't get three states in the United States to agree on a universal spelling/pronunciation let alone the three countries in the United Kingdom. You think you'll have any more success over continents and across oceans?
> Spanish, French, written Chinese, etc. all had a monarchy/dictatorship of some sort to mandate the change and enforce its use.
There is no central authority over the Spanish language since the days of Bolivar and San Martin (1810s or so). Modern e.g. Argentinians would laugh at the idea that Real Academia Española has any say on how they should use their language. And indeed, there are differences not just in vocabulary and pronunciation, but also in grammar: "vos hablás" instead of "tú hablas".
Nevertheless, I can pick pretty much any written Spanish word and know how it sounds both in European and Argentinian Spanish.
It is specifically English which failed at the task of not being like Chinese.
This is what some people advocate for English - entirely misguidedly in my view.