IS: present or passive

[logicgate]

How would you understand and translate

> Hoewel de samenhang niet wetenschappelijk is bewezen, bestaat er geen twijfel over.

?

To me, "is" here is the past passive so that it should be

> Although the link has not been proven scientifically, there is no doubt here. (1)

But can it also be interpreted as the present tense, were bewezen is an attribute adjective, so

> Although the link is not proven scientifically, there is no doubt here. (2)

In any case, how would you translate sentence (2) in Dutch?

I am conscious that it is a subtlety here since what has not been proven is "not proven" and reciprocally. But there might be cases where the meaning of the passive and active forms show more difference. Is there sometimes an ambiguity for Dutch people, when interpreting "is" as passive past or active present?

[brucetraskV2]

How about
Hoewel de samenhang niet wetenschappelijk is te bewijzen, bestaat er geen twijfel over.

which applies this point https://www.dutchgrammar.com/en/?n=Verbs.Ot09

and would translate to "Although the correlation cannot be scientifically proven, there is no doubt about it"

So there is a presentness about it.

[logicgate]

Many thanks!

My broader question is whether there is an ambiguity for Dutch native when interpreting a verbal form with zijn, between the past passive and the active present with attribute adjective. I hope it is clear<