I'm using Windows 7 64-bit, with ID 2014 to produce the ePub.
I just created another ePub, using Fontbit Shaked, 4 different weights
(light thru black). I then uninstalled the fonts from my system, and
opened the ePub in Readium. Everything displays fine. (I'll be happy to
send you this ePub to test yourself if you give me your email address.)
So I'm not sure why you're having trouble. Obviously -- you have checked
the option "embed fonts" under the CSS tab in the ePub export dialog, right?
So it seems to me that InDesign has no problems embedding Hebrew fonts
in ePubs. The problem is almost certainly with various ePub readers not
displaying the embedded Hebrew fonts correctly. But as I say, Readium
seems to be working fine in this respect.