It shouldn't be a problem becuase they are DRM-free.
I found with an older eReader (Cybook Opus) that there was a small number of books it couldn't read ~ somehow it didn't fully understand the .epub format.
Being DRM free gives you more options to experiment.
I suggest trying to use the free Calibre software to read the books and transfer them to the Kobo. http://calibre-ebook.com/
It can also do reformatting of books, so might be able to correct issues in the books that upset the Kobo.
Calibre is vastly superior to ADE (not very difficult); with the major limitation that it can't handle DRM books.