citations - how reference a translation of an already translated text?

Somebody wrote a text in Latin, let’s call her Alice and let’s call the text De Nihilo. This text was then translated into German by Bob. In my work, I translate Bob’s translation into English.

In the author–date system of the CMoS style, I have adopted this solution for referencing a translation of an already translated text:

My own translation of the following translation from Bob. (Bob 1987; translation in German of De Nihilo by Bob).¹

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^{¹ “[Latin Text]” (Alice 47BC).}

Is my solution the correct one?