> For any "real" language it's probably impossible to have a 1-1 mapping in both directions.
Ukrainian is pretty close. It helps that it doesn't have a lot of reduced vowels that sound indistinct, and that double consonants are very unusual. The only ambiguous part is stress, technically stress marks exist, but they are used only in dictionaries.
In fact, most Slavic languages are _reasonably_ close to 1-1 mapping. Some are closer, some are further. For example, Russian has a lot of reduced vowels that you have to remember how to spell.
Ukrainian is pretty close. It helps that it doesn't have a lot of reduced vowels that sound indistinct, and that double consonants are very unusual. The only ambiguous part is stress, technically stress marks exist, but they are used only in dictionaries.
In fact, most Slavic languages are _reasonably_ close to 1-1 mapping. Some are closer, some are further. For example, Russian has a lot of reduced vowels that you have to remember how to spell.