If you are comfortable making HTML from your Word documents, I was able to print Hebrew text strings to Kindle KF8/Fire (phrases, not whole documents) using HTML with CSS tags.
font-family: 'Hebrew', serif;
In your HTML, you need to call the .hb class in your P tag:
<p class="hb">hebrew text</p>
If all the text is Heb, I suspect that it will work better if you wrap each paragraph in the P with hb class rather than applying it to the body.
I don't know how complex your formatting needs are, but if they are simple, you could get away with Word find/replace paragraph breaks (^p) with
This will wrap every paragraph in your Word doc with the needed HTML tags needed. Export (save as) the file from Word as text, not HTML/Webpage (mind your encoding). From here you need to work in a text editor, not Word You will need a HTML head and foot for the top and bottom of the file.