Are we supposed to make corrections to our code every place we use Read/Write and every place we use toAnsi/ToOem?
yes you are!

In fact, the compiler raises the waring for you, exactly for that.. when you use any of those functions.. toAnsi/ToOem , exaclty to make you review them!

Please read these 2 chapters..
DataFlex 2023 Help - Unicode 101 (

DataFlex 2023 Help - Unicode in Dataflex (

There is no right answer .. The answer is.. it depends on each case.
If after reading these 2 chapters you still have questions, come back with them ..