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?

[logicgate]

Another example

> De belofden van het coalitieakkord zijn niet gevolgd door concrete maatregelen.

Is it understood as a past passive form, or is there for Dutch native an ambiguity between

> The promises of the coalition agreement have not been followed by concrete measures.

> The promises of the coalition agreement are not followed by concrete measures.