Encodings Mac/Win French

I have to admit I have struggled with this most of the day.
Just when I think I have it correct it pops the strangle symbols in place of normally the end character.
I have a plain text file, I tried using Word to check and save out. The Mac side was fine when I used MacRoman but now I have the windows side I tried to use UTF-8 to satisfy both.
Sample file

It is a simple format Word : Defn
I use this format as the user can edit or create their own.
English seems to work on both platforms but as soon as I use another language I get the weird characters.

Without code it’s hard to say what is causing your problem. I’d guess that you crossed your EndOfLine characters somewhere. This has nothing to do with utf8.

Try to avoid anything that is not UTF (UTF-8).

ASCII gives the same values/characters for code 0-127.
In the pre-UTF-8 times, MacOS had its 128 to 255 codes while WIndows have a different one.

For this text file: in Xojo, use UTF-8 for reading and witting and you will not get troubles whatever OS your application is running.
Use TextInputStream / TextOutputStream.

Using MacRoman will lead you to use Windows1252 and so many other encodings fom the past when you should use the normalized one (UTF-8).

Your document opened in Firefox on El Capitan is displayed in the WIndows1252 encoding… to be able to read it correctly in Firefox, it must be embedded in an html document who specify the correct encodings (UTF-8, <meta charset='utf-8'>).

Outside of Xojo what would the safest way be to create UTF-8 text files (in languages like spanish, french, german, english) that my program could then import?

Use TextEdit by Apple, for example.

In fact avoid old versions of software, uses versions released recently (one or two years) like LibreOffice for example.

I do not used a Microsoft application since… 30 years ago, but in these times, at each major OS version change, everybody had to update its Word, Excel, etc.

Do you remember the 2K0 bug ?

word and excel really don’t know about utf8. they use macroman and window1252 depending on the platform they run on.
even the last versions
use textedit,
or bbedit (free version) to see what is the encoding, and to be able to change it.