While allowing posts in any language would be problematic for our site (as discussed here that we need a user base "capable of answering, evaluating, voting on, improving, maintaining, categorizing, moderating behavior, etc."), it seems to me that as a byproduct of attracting a community of experts in Judaism we have also attracted a significant community of [rabbinic-]Hebrew-readers (if not -speakers), not to mention a number of users who live in Israel. We regularly have posts citing Hebrew works which users [seem to] follow up with, for instance. Thus it seems to me we can handle posts in Hebrew to a sufficient degree.
Obviously, we would need guidelines for how to implement this. (Possible guidelines could include: Hebrew answers not allowed on English questions (vice-versa?) so questioners will be sure to understand answers given to them, a hebrew-post tag for easy filtering, link in post to a "Hebrew post policy" on meta, etc. These would be figured out later here on meta. We could consider other things too like electing another moderator who is fluent in Hebrew or allowing Hebrew questions for a trial period (2 months?) to see how the site handles it.) If a user can't understand a Hebrew post, they simply have no need to vote on it. This isn't that different from a Python programmer skipping questions about R over on Stack Overflow. I don't expect we will be overwhelmed with these posts, and if we ever are it probably means we're gaining more users to help maintain them (after all, millions of Jews speak Hebrew better than English).
I note that obviously adding a translation to English would make the post more accessible to more people (just as adding a translation of an English post to Hebrew would make it more accessible to more people). But as you say, in some cases and for some people Hebrew is better for them (eg. they are more comfortable in Hebrew than English and their topic is such that they will get a satisfactory answer even asking in Hebrew to a (currently) somewhat narrower audience). If someone wants to go add a translation, that only helps so good for them, but until then, if we have the tools to accommodate it in the language the OP prefers, maybe we should.
Please vote on this post based on if you think we could gain by further exploring this option, NOT based on if you don't like a particular detail/guideline above or just don't think we are ready to commit to it yet. You are not voting on a final policy.