Where can I find epub files of translated LNs and WNs?

Well you can make your own otherwise unless a translator offers it i REALLY doubt you can find one

You can search for it on wattpad too it has offline read option

I personally keep their window open on plane and read as i go 

Please do not publicly request or provide assistance with piracy on the forums.

The only legitimate source of epubs for WuxiaWorld novels is WuxiaWorld, and you pay for them. If they do not offer them or you cannot afford to pay for them, acquiring them from a third-party is piracy.