Hi Micbaldur.
For the revenge part: the Note of a Scoundrel is part of The Request of a Noble Lady so possibly you did not finish the quest.
That part should lead you to Copper Coronet where you find Velero in a back room. If you missed this part it might be you also missed some other parts around. Not sure, just guessing.
Thanks for the translation
Hei Nightfarer.
I took Velero to Bylanna ages ago (like note says he's should be in prison) but i check this Velero case later tonight.