(Alain here!)
One intriguing possibility will be to have MULTIPLE pivots 😁
Even if a translation is mostly based on one specific version (the original or a pivot), nothing forbids from checking others for better results.
It actually happens quite a lot professionally, where we work from English to Italian but often get good ideas from other romance languages.
Have fun! In any case, retranslation will be explicitly allowed by the license, just make sure to mention your sources!