I know you are learning to be a Plex Developer but you still need to read the code!
you need to read the action diagram and read help, it is all there.
You need to understand the function flow which will lead you to:
Sub TabStrip add tab
------- VB Script
Set Tab = TabStrip1.Tabs.Add(&(2:),,&(1:),CInt(&(4:)))
Tab.Tag = &(3:)
The solution offered is piggy backing on the the ADDING of tabs....during initialisation ...what you want is AFTER initialisation in some circumstances...so you will need to search for the VB Script to update text (if it exists which I dont think it does), or you could reload the whole parent which is where the tabs Text is located.