Extended ascii character conversion?

Is there an easy way to change characters from the extended ascii set to characters roku can display as standard text?
ie

Citro�n Berlingo Multispace � Pagani Zonda � Lamborghini Murci�lago � Mazda6 Speed Cameras Harry Enfield

FFFD to say, a standard “e” and FFFD to a “.” or something to handle every noncompatible character automatically without requiring a separate executed line for each character possibility? I’m looking for an easier solution - like to take the character value and if it’s >128 then subtract some value from it to get a standardized alphanumeric character?

U+FFFD is already a “replacement character” which means whatever was there has been busted already by previous “conversion”, it’s displayed to indicate there was unpresentable character here.

Assuming is there generic solution to replace unicode symbols that have no presentation in particular font - no, since you don’t know which characters are implemented in each TTF, nor is it clear what you (the author) would consider reasonable substitution. For example is it reasonable to replace “™” with “™” and “©” with “(C)”? Maybe yes, maybe no because it may change the text alignment.