Here’s why I recommend against translating from a translation:
A lot of TLs extrapolate from the original line to find a line that best fits the feeling of the original. This means that the line in the 1st TL’s lang is going to have nuances that don’t exist in the 2nd TL’s lang.

Because the 2nd TL doesn’t have the the base, original line to work off of, it will be translated so it captures the nuances of the 1st TL, which leads to an interpretation of an interpretation. This is exacerbated by any use of idioms not easily transferred into the 2nd lang.

Even worse, the 2nd TL might translate from the 1st too literally, which further compounds matters. It becomes a game of telephone, and a lot of the original meaning is literally lost through this process.

Of course, this doesn’t always happen, and it largely depends on the languages involved, but it’s not a practice I can get behind because of these aforementioned reasons.