Is there a way to view/filter only unicode fonts?
I would like to preview only Arabic fonts.
I assume you mean MainType.
No, you cannot currently filter fonts by script, such as Arabic. However, you can enter some Arabic text in the preview and then scroll through your fonts.
Fonts that do not contain all characters needed to display the text will show the missing characters in red. In Options > Font Lists, make sure Show preview with missing characters in red is enabled.
If your preview text is short, you can also switch to Grid view, which makes it easier to quickly browse through many fonts.
Once you have found the Arabic fonts you want to keep track of, you can assign them a tag such as Arabic. Next time, you can simply search or filter by that tag.