Rename {{temp|ar-numeral}} to {{temp|ar-cardinal}}?

Well, you'd have the same objection with just "numeral", I suppose. The thing I was trying to avoid was people thinking that {{ar-numeral}} is useful for e.g. Abjad numerals like ب or Eastern Arabic numerals like ٢.

Things with numbers and numerals are kind of confused, and they were a rather contentious issue for a long time. No consensus could be reached and so things were left in an indeterminate state with multiple conflicting uses of terms and categories. For example, there were "numeral", "number", "cardinal numeral", "cardinal number", "ordinal number" and "ordinal numeral" categories all containing similar entries, with different languages using different names.

Now, we've settled on this situation:

• "Numeral" is considered a part of speech, and contains all (cardinal) number terms that are not clearly members of another part of speech. These entries receive the ===Numeral=== header.
• All cardinal number terms, regardless of part of speech, go in the "cardinal numbers" category.
• All ordinal number terms, regardless of part of speech (although they are generally adjectives), go in the "ordinal numbers" category.
• Symbols for numbers, such as 1, 2, 10, 12 go in the "numeral symbols" category. These entries receive the ===Symbol=== header. (For languages like Chinese, there's not a clear distinction here because all symbols stand for concepts. There's little difference in Chinese between the word for the number 1, and the symbol for it.)

I hope that clears things up some.

Where did this consensus come from? Is this just your take on things (not that I'm objecting necessarily)?

I recently edited the Eastern Arabic and Abjad numeral symbols so the heading says ===Numeral symbol===. If you think this really should say just ===Symbol=== then I won't object but would ask that you make the change yourself since you're comfortable making global search/replace changes and I'm still figuring this out.

I don't really remember. I think the consensus was "this mess needs to be sorted out" but nobody could agree on how. Eventually someone (me I think) came up with an idea and it was adopted, but I don't remember the details. If you do a search for number/numeral in the Wiktionary: namespace you'll find the countless discussions about it.