Are you on one single ticket?
Any checked bags? If so, do you think those will be checked through to CCU.
Do you think you'll have all your boarding passes issued in EWR?
While these aspects do not affect your lounge access - on the plus side the
LOUIS TAVERN LOUNGES
Concourse F Level 3 (Business Class)
Concourse G Level 3 (Business Class)
are open 24 hrs.
Your time and procedures at BKK may be affected. Checked bags through, and one single ticket, then int'l-int'l midfield connection should be possible, with or without (Connection Counter) BP for BKK-CCU.
If say, any bags are only checked through to BKK then this means you'd have to clear arriving Immigration, retrieve bags, clear Customs, then head up to level 4 where you may not be able to check in immediately, then you'll have to clear departing Immigration.