LibreOffice V.6 has a very good export in ePub, both ePub2 and ePub3.
Under the menu File>Export As… you can find this option.
The next version of Writer2ePub for LibreOffice will be just an helper for composing a good ePub, but the creation of the ePub itself will be done by LibO.
Thanks for your interesting in W2e