directeur principal, ventes techniques

13:24 May 7, 2019 

Had the original term been 'Technical Sales Director', there would have been built-in ambiguity, as to whether it means 'Director' for 'technical sales' or 'Technical Director' for 'sales' (what your customer seems to want)
But as it stands, the EN word order seems to be fairly unambiguous — although one might wonder if the term is actually originally translated into EN from FR (or some other language) in the first place? I wonder if your customer knows something we don't...?

12:59 May 7, 2019 

Hi, which industry is involved?

01:15 May 7, 2019 

Responsable technico-commercial, Directeur des ventes techniques, Directeur technique commercial.