[SagelyGuru]

It is worth mentioning Jan Hus: Orthographia Bohemica, 1406 https://en.wikipedia.org/wiki/Orthographia_bohemica which introduced diacritical marks to facilitate expressing all the sounds of Slavic languages in Latin alphabet by single symbols. They have logical phonetic meanings, for example háček (the hook) indicating the placing of the tip of the tongue on the palate. Though, admittedly, they are somewhat inconvenient on modern keyboards, usually relegated to the top row.

Jan Hus was later burned at the stake for his 'heresies', which probably slowed down the uptake of his eminently useful invention in the rest of the world.

It is my opinion that even English more than 600 years later could benefit from it, as in: 'caš ček' instead of 'cash cheque', thus also finally attaining much simpler, logical and phonetic spelling.