I'm using the LibreOffice OnLine instance found on the TDF nextcloud server. My NC account is setup with English(USA) as my default language. The NC user interface and LOOL UI are both displayed in English. When any new file is created (odt,ods,odp) the documents language is st to German(Germany). The spell checker also does not work initially, either for misspelled German words or English (though I expected the later to not work). Explicitly setting the language for the document to English(USA) works fine and automatically starts the spell checker working. BTW - In the special case of Calc files the three sheets created by default are using German strings. (though that might be a separate issue, huh?)
Yes, this happens because templates are actually empty regular document/spreadsheet/presentation files with a set language, which is German. To meet the expected behavior, proper template management has to be implemented.
With the latest LOOL templates are more fully supported. I've been working with the LOOL via a NC server at TDF and using Templates with language and local set to en_US. Still some problems though particularly with the local settings and specifically when displaying dialogs. Where in the dialog settings do not match the local settings used in the template a new file is based on.
Also - the problems are not just with ODF templates, new documents based on OOXML templates have all the same behavior.
Fixed by the following commits in NC and oC richdocuments: https://github.com/nextcloud/richdocuments/commit/56439d25a22974d6f71993fb2b63461e20386866 https://github.com/owncloud/richdocuments/commit/27021cf1fdd5ad01a3488d85081f1c09e2bfffde Templates are based on bug 133661's minimal templates.