Does Improvisation allow a character to make knowledge checks above DC 10 for knowledge skills in which they have no ranks?
Prerequisites: Int 13, Fast Learner, human.
Benefit: You gain a +2 bonus on all skill checks for skills you have no ranks in. Furthermore, you can use all trained skills untrained.
Untrained: You cannot make an untrained Knowledge check with a DC higher than 10. If you have access to an extensive library that covers a specific skill, this limit is removed. The time to make checks using a library, however, increases to 1d4 hours. Particularly complete libraries might even grant a bonus on Knowledge checks in the fields that they cover.
My impression is that the wording of Improvisation does not overrule the clause about knowledge checks because you are still untrained. This would make Improvisation only really worthwhile on the other trained skills and for the bonus to skills you haven't invested a skill point in.