Although I admittedly haven't been using Mellel in recent years as much as I used to, I always keep it current as I have hundreds of documents from previous years created with it. I would guess that it still probably handles right-to-left languages on the Mac better than anything else, even with MS Word improving tremendously (finally!) in the most recent version.
Mellel 4 has been released in the last couple of days, and it's worth looking at if you're doing any kind of academic writing on the Mac or working with Hebrew, Arabic, and other RTL languages a lot.
If you have the Mac App Store version, it is not a free upgrade, but is considered a separate release. However, MAS users of Mellel 3.x can get an upgrade price by clicking on the link here that will install a non-MAS version of Mellel 4 and will migrate all your v. 3.x settings and content over to v. 4.
Mellel has always had a little bit of a learning curve because it's never been "just another word processor," but instead a word processor rethought from the ground up. In other words, don't expect that because you know Word or Pages that you can just jump in and get going. You need to invest some time in learning. That's not to suggest Mellel is complicated; rather, it just works differently. Fortunately, they have really beefed up their tutorial section for Mellel 4, including quite a few new videos.
Mellel also works really well with bibliographic management software, Bookends, which I have continuously used for over a decade, even as I have bounced around at times to different word processors (Bookends works with just about everything). If you want both programs and have neither, there is a discounted combo purchase price available. If you already have Bookends and want a discount on Mellel, you will want to fill out this form.
This is a totally non-compensated endorsement--I have no direct ties to Mellel or those behind it (or Bookends either). However, looking at the new version of Mellel, I admit that I am tempted to go back to using it more regularly.