there's a slight difference b/w authentic and genuine, but you may want to consider it anyway. Other options: authoritative or boda fide, or even real or trustworthy.

"Stage presence" for Auftreten in certain contexts.

gives the impression of being the true character he presents himself with; not a pretender

I know it is a slightly free rendering of the ST but it seems to be used fairly commonly in texts related to job interviews..

Sollte es sich hier um einen Unterpunkt fuer Unternehmerkompetenz bei einem z.B. Assessment Center handeln, wuerde ich eher aktiv formulieren, da es um beobachtbares Verhalten geht:

appears anstelle von Appearance
authentic wuerde ich entweder als authentisch belassen (dasselbe Wort existiert schliesslich in beien Sprachen), oder als believable uebersetzen.

Think this is a bit like "souverän".

in the context of the other bullets, I would write:

-socially skilled
- emotionally stable; able to set boundaries
- mature
- sincere

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simply... it's what makes Gutenberg so popular

perhaps ?

In my opinion, there are two elements involved in these "authentic dealings with others": one is being honest, frank and open (not a bull****ter); the other is being a practical realist (someone who comes across in a way people can relate to and understand)