@tintin,
Renaissance is French, and is used so commonly in English, that it is become a common noun. Renaissance means a rebirth. Therefore,
Cross-border collaboration is experiencing a modest renaissance . . . , means that cooperation between neighboring nations is experience a modest rebirth. A cartel is a group of businesses or nations which operate together to seek an advantage. An oil cartel would be a group of oil companies, or oil producing nations which operated together in the hope of getting the most money from their product. Brisk in this sense means fast and heavy, so,
. . . even if business from a joint venture by several cartels is less brisk and profitable than by a monopoly. means that the business from the joint venture does not move along so rapidly, and does not enjoy the same heavy volume of business on the part of a monopoly.
Yes, "one upside" (terrible abuse of the language) does mean one piece of good news.