Painseeker gloves and Bonechill Support

Do they synergize? Will the damage taken increase granted by bonechill be greater thanks to having Painseeker equipped?

Why not? Bonechill only cares about chill from linked skill being present on an enemy, not about how that chill was calculated.

Moreover, you don't have to link bonechill to your strongest chill source. As long as chill with attached bonechill is there, bonechill's effect will use highest of all chill effects in there for its damage taken amplification. Even if this highest chill did not come from the linked skill.

However, painseeker won't boost chill and bonechill cap, it merely makes it easier to reach that cap.

hmm right. is there any way to increase max chill effect to above 30%?

Elementalist ascendancy

that the only way?

yep