Mutually Unintelligible Dialects: some conlang ideas

I’m working on a conlang commission and reading Between Home and Ruin, both set in the future, where English has splintered into several dialects united by a common written language. This is a fun idea and a plausible one - Chinese and to some extent Arabic work this way. English arguably already works this way. There are people in Jamaica and Scotland whom I won’t be able to understand when they speak (see Jamaican Patois and Angry Scottish People Using Real Words Maybe) unless I have subtitles written with standardized spellings.But how exactly will that spelling system work? I did some experiments with English’s closest cousin (that is also a national language): Dutch. Example 0:
De Nederlandse krijgsmacht is de militaire organisatie van het Koninkrijk der Nederlanden. De krijgsmacht wordt in de kern gevormd door de vier krijgsmachtdelen: de Koninklijke Marine, de Koninklijke Landmacht, de Koninklijke Luchtmacht en de Koninklijke Marechaussee. (from wikipedia)
Dutch and English parted ways between 1,600 and 1,400 years ago. In that time, they accumulated three kinds of differences: pronunciation differences caused by sound changes, grammatical differences caused by regularization, and vocabulary differences caused by coinages and loanwords.
Forcing Dutch into standardized English spelling* will cover up only the first difference. Example A:
The Nederlandse Criesmight is the militarie organization fan the Kingright ther Netherlanden. The Criesmight wortht, in the corn, geformd through the four Criesmightdealen: the Kinglie Marine, the Kinglie Landmight, the Kinglie Loft Might, and the Kinglie Marshalcy.
Remember that Example A above is still pronounced as Example 0. It’s just been spelled so that it’s easier for speakers of the “English dialect” to read. But is it easy enough? Maybe the Spelling Standardizers do away entirely with phonetics and translate the grammatical morphology. Speakers of the “Dutch dialect” have to remember to write <-s> when they say /-en/. Example B:
The Nederlands' Criesmight is the military organization fan the Kingright the's Netherlands. The Criesmight worths, in the corn, a-formed through the four Criesmightdeals: the Kingly Marine, the Kingly Landmight, the Kingly Loftmight, and the Kingly Marshalcy.
Or they go further could go further and simply translate words not found in English. Dutch speakers would say /krijg/ but write <war>. Example C:
The Lowerlands' Warmight is the military organization of the Kingdom of the’s Lowerlands. The Warmight is, in the core, formed through the four Warmightdeals: the Kingly Marine, the Kingly Landmight, the Kingly Loftmight, and the Kingly Marshalcy.
We could go farther (Warmight > Warstrength > Armed Forces). Where we stop is a matter of taste and practicality. Which brings me to the question of how this writing system would actually work.

This message consists of 6 "words" and 25 "glyphs.” Since glyphs are like Chinese characters, the second one in the table might be pronounced /war/ or /waa/ or /krijg/ (as in this case) or any other way.
If you pronounce it like 21st-century Dutchman, you would say, "de-ned-er-land-se krijg-s-macht-is de-milit-aire organ-is-atie van-het-konink-rijk der-ned-er-land-en."
If you pronounce it like a 21st-century American, however, you would say "the-lower-land-s' war-might-is the-milit-ary organ-iz-ation of-the-it-king-right the's-lower-land-s."
Although you'd probably understand it, you'd know you were reading something written in a non-American dialect. The standard way to write the same message in the American dialect would be:

"the-neither-land-s arm-ed-force-s-are the-milit-ary organ-iz-ation of-the-king-dom of-the-neither-land-s."
As an educated person, you would know to pronounce <is> as /ar/ in this sentence, and you’d know that <neither> doesn't actually mean "neither"; it's just a phonetic approximation of /nether/, a marginal word that has no dedicated glyph.
The next step will be to make a better mockup using Krita and a Times New Roman typeface. And I’m waiting for the guy who’s working on the future standard of English. Then I’ll start working on the 3-4th alien creole derived from it.
In the mean time, what do you think?
*why not force English into standardized Dutch spelling? Because this is practice for a scifi story written in English. The future English-alien creole of the commission has nothing to do with Dutch.
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