I sent my documents to WES.org/ca and it is in process of evaluation. For Transcripts from TU I had official sealed transcript from TU which I included in my packet. and I included my copies of diploma from US univ. I asked for official transcript with the univ here and they send my offi transcript to Wes.org/ca. I am waiting for my final evaluation.
I think it should not be any problem if you have official sealed transcript from Nepal.
For school no longer existing I don't know if you're talking abt Nepal or here in US. I have no idea.