According to
the oUF Hank page on CurseForge, the layout is licensed under
the LGPL, which means you are free to modify it and distribute your modified versions.
If you have truly tried every option for contacting him (including PMing him on CurseForge and/or Curse) and have not gotten any response after a few weeks, then I'd suggest contacting the admins/mods here and on CurseForge to request access to the addon's pages so you can post updates.
However, before publishing anything, you should think about whether you really want to take on the responsibility of keeping the addon updated. If you're just going to "fire and forget" -- post an update and then never answer questions, address bug reports, or post any future updates -- then please don't bother.