Are soldering fluxes safe to touch?
There seems to be a translation issue, and it's a good job you asked the question; this is not the roisin flux commonly used in electronics, but Zinc Chloride (if my machine translation of the German datasheet is correct).
Zinc chloride is mildly corrosive - indeed, that's partly how it works, it's intended for soldering bulk copper in plumbing where removing the copper oxide layer is important.
I wouldn't panic about it but it's in the same category as kitchen cleaning chemicals where mere contact will sting a bit and you should wash it off promptly.
(Labelling it as &quot;soldering paste&quot; is even more confusing in English, because &quot;solder paste&quot; normally refers to tin or tin-lead particles in suspension used for automated soldering in ovens)