"sufficiently known" is a correct and usable phrase in written English.
You can use it to describe a situation in which something is understood or familiar to many people. For example, "The theory of evolution is sufficiently known that most people understand the concept."
That pancakes save lives is not sufficiently known.
The optimal degree of intervention is thus not sufficiently known.
At the present stage of research, the only judicial system sufficiently known to warrant description is that of 4th-century Athens.
He doesn't have to rely on the money of others to become sufficiently known in order to have a chance; he has his own money (even though just how much he has is disputed).
Optimization of these factors to maximize the toxin yield is largely empirical at this stage because the mechanisms of action of these factors on the algal growth and toxin biosynthesis are not sufficiently known.
Because knowledge of the spectral properties of the operator is not required, the method is also of interest in regular cases where these spectral properties are not sufficiently known or are hard to deal with.
I have a lot of sympathy for them, but I often find that they do not sufficiently know their stuff.
Furthermore, it is important to evaluate whether the attending physicians sufficiently know the preferences of their patients to consider them adequately in (mutual) treatment decisions.
There remains much to militate against the potential for happy outcome; it is a truism, for a start, that the legal system will tend to agitate – and, when parties are sufficiently well known or when settlements sufficiently spectacular, so will the accompanying headlines.
However, the incidence of falls is sufficiently high and the risk factors for falls are sufficiently well known, for it to be feasible for falls programmes to be delivered to those identified through screening.
It is a tragedy that is not sufficiently well known.
