@Pea Proximity is a factor for the world map, influences tributes and trade. A proximity below 100% (or 1) means there's additional effort to be done to ship the wares. Therefore you get less tribute/taxes from other provinces you own and trading becomes less efficient.

For me personally, the mod is somewhat obsolete in V65, since the road has 3 stages to build and the first one already offers 0.25 proximity, which already lasts for significant distances until that problem kicks in again.

I dont understand what this means? Bonus from being close to world-map roads?