@sdetweil
Thank you sdetweil for your message.
I have tried several timezones for the system upper right on the pi desktop.
It has no effect on the times displayed on my calendar on Magic Mirror, still GMT+0 instead of GMT+2 on my Google Calendar.
I have also tried different timezones in Google Calendar.
It has no effect either on my calendar on Magic Mirror.
It seems that Google Calendar uses UTC time in .ics files.
Now the timezone is set correctly on my system.
The problem should be in my configuration of the module MMM-CalendarExt2.
I have just put the line forceLocalTZ to false, and at last, both calendars on Google Calendar and on MMM_CalendarExt2 are synchronized !
It’s a bit strange as I thought forceLocalTZ:true should force the time to my local timezone and the contrary happens ?!
But the problem is solved.
Thanks a lot for your help.
Cordial greetings.