Unless you have modded your tarp and added over 40kg of bling, diamante, food pockets, axe holders and I am running out of silly ideas here, it should be ok.
There will be more stain on the ridge then just the simple weight of the tarp but if you do not have the hang so tight that the ridge is perfectly flat it will not go close to the 50kg.
By this I mean that there is a reasonable amount of dip. I have seen some setups where the tarp is almost ironed flat the rig is so tight. That could be easy over 50kg of strain. Yes it will shed water fantastic but the odd winkle and dip is not the end of the world.
For the main I have rarely got my hang loverly and tight. The spot where the tent pegs go is just not right...I have pulled one side too tight before setting the other side... haveing got it set set up just nice I change my mind and lift one part with a pole to give better head room... all of which mean that a less then perfect hang still keeps me dry in a down pour. If there is any pooling ( there will be !!!) it is able to drain before becomeing an issue.
From a different point however is the idea of a widow maker. There can be a real chance of a branch falling and landing on your tarp and then on you. A paracord ridge will be of little help. In the past I had all but dissmissed the idea until.... the sound of a cracking branch and the noise of the fall once heard can not be forgot. It was not in any of my trees and it was not within sight but the sound was unmistakeable and not easy forgotten. I now use a webbing strap as my ridge line.