As announced in EPUBCheck revision initialized post, a maintenance release of EPUBCheck as been published in time by the DAISY Consortium.
This version 4.1.0 includes various improvements and bug fixes that have been contributed over the past two years. See https://github.com/w3c/epubcheck/releases
And now, en route for EPUB 3.2 validation.
You can still continue to support this work by contributing to the fundraising call at https://www.w3.org/blog/2018/10/epubcheck-fundraising/