I agree with Brian that:
- the gloss should be "the depth of one's knowledge/achievement". 
- it's not worth keeping.

造詣深い	2709	3.9%
造詣が深い	36677	53.0%
造詣の深い	29797	43.1%
This and related terms:
造詣の奥深さ	20	0.0%
造詣が奥深い	0	0.0%
造詣の奥深い	0	0.0%


奥深さ	252417

probably incorrect gloss.

A+B

ngrams: 20
twitter: no results
~2 quotes come up in some news results.
Only about 4 obvious book results(several copies of the same text pop up).  

I think the gloss is incorrect.  Should be, I think, "the depth of one's knowledge/achievement". 

Example book result:
"In order to know the depth of [his?] knowledge..."
『回想九十年――師化全般の造詣の奥深さを知るためには、なお数巻の書物の編纂が必要であろう。術と』

Very little reason to have this.  By comparison, of the top of my head, we don't have this either:
知識の奥深さ	261

https://eow.alc.co.jp/search?q=人の知識の奥深さ
（人）の知識の奥深さ
profundity of someone's knowledge