Not all languages are available for all regional versions (e.g., Archicad US vs. Archicad INT).
You can have multiple localized versions of the same Archicad release installed on a single machine simultaneously. Graphisoft Global Library Localization (Archicad 28 & Later) With the introduction of the Global Library
You can prioritize language settings for library parts by going to Window > Toolbars > Edit GDL Library Parts and selecting Library Localization Preferences .
For official details, search Graphisoft Help Center for: