Govind, 08/09/2016 12:03:

I'm experimenting on revision history dumps of Wikipedia.

Do you mean the English Wikipedia?

I've confusion
regarding archiving of Portal:Current Events in revision history dumps.

The title you mention only has 2 edits: https://en.wikipedia.org/w/index.php?title=Portal:Current_Events&action=history
The target page has 2100 edits: https://en.wikipedia.org/w/index.php?title=Portal:Current_events&action=history

Do you expect more? Note that of course most activity happens in the transcluded pages: https://en.wikipedia.org/w/index.php?title=Portal:Current_events&action=edit

Nemo