The OP asks what effect would there be on religions if science discovered the creator of the universe as an object for all to verify.
Since such a creator would be an object found by solving a scientific problem, religions could counter by presenting that object as an idol unworthy of worship by any believer. Without the individual person's participation in worship it does not matter what science offers as objects of worship.
To see how a believer might deny any such scientific discovery, consider Kenneth T. Gallagher's description of the thought of Gabriel Marcel, a Christian philosopher, regarding the difference between problems and mysteries. Here is Gallagher describing Marcel's view of an object: (page 37)
We have seen that an object is indifferent to me; it is simply there "for anyone" (and ultimately, Marcel says, this means that it is there for "no one"). Because this is so, it follows that the self as conscious of an object is just anyone, an anonymous, impersonal mind for which any other mind might just as well be substituted.
The object exists in a public space. It is a "third in a dialogue". (page 30) Gallagher describes Marcel's view of faith: (page 37-8)
The rationalist would like to say to the believer: "You think your belief bears on a real being, but if you were in my position you would see clearly that you are the victim of an illusion." His remark implies that he can put himself in the place of the believer and correct the latter's vision. This assumes their places are interchangeable, and this is just what Marcel is moved to deny, holding that the subject of the act of faith is a singular self whose place absolutely no one else could take: his "place" is his being, his unique self. To take my place the other would have to become me. This, of course, means that my faith is absolutely unverifiable by anyone else, for only what is available for all can be verified.
The objects found by science would be verifiable by all. They exist in a public space. The faith of a believer, a unique self, would be unverifiable by anyone else.
Let's consider the questions:
What effect does this have on religions? Does this evidence suffice? Or will religions assert that their 'god' created these beings too?
Finding the object would likely have no effect on religions. That the evidence is verifiable may be used as evidence against it that what has been found is merely an idol.
In the latter case does it mean that God can never be known?
Here is how Gallagher presents Marcel's view of knowledge: (page 35)
As with my body, the world, evil, so with love and knowledge: these are realities about which an observer can pass no verdict whatsoever, for they are only real for the participant....If I say "what is knowledge?" it is all too obvious that I immediately plunge into the realm of mystery. For I can in no way get outside my own act of knowing in order to treat it as a possible object of description.
One could know God by participating in the faith of a believer, a kind of mystery of being. So knowledge of God would be possible.
Gallagher, K. T., & Marcel, G. (1963). The Philosophy of Gabriel Marcel.