RichTextEditor Globalization doesn't work properly. The translations are not available everywhere. It seems like the localization applies only on popups (e.g. add picture) but not on dropdowns (e.g. text alignment).
This behaviour can bee reproduced on the corresponding documentation page: https://ej2.syncfusion.com/documentation/rich-text-editor/globalization/
(Last updated on: June 24, 2019).