I installed GanntProject on a MacBook Pro with Swedish as my default language for the Mac. It resulted in invisible and non-functioning display commands that are supposed to be shown above the calendar bar in the Gantt view. There was no zoom, past <–> future, Show critical path, or Baselines commands. Clicking where I knew they should be (from watching YouTube tutorials) made no difference.
Only when I changed my primary language on the Mac to English, did these command features appear, and function.
I hope this helps people with other languages than English, in case they aren’t finding how to display the critical path and baselines.