Usually LIbreoffice gets it right, but if it opens a normal English CSV as UTF-16 by default and shows Asian languages, you'll have ot manually open to fix it (don't double click the file from the File Manager).
Solution - Manually Open the File After Opening LibreOffice Calc
You'll see it is defaulting to UTF-16 which breaks everything.
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Login as Admin
Languages & Phrases -> Search in Phrases
Choose "Phrase Variable Name Only"
Search for: welcomemail
Edit the "Translation" box with what you'd like in it.........