No we don't know why Cohen plead guilty to those charges. Your assuming you know. What your failing to understand is Trump directing an attorney to do something legal isn't illegal. This is one of Jarrett's points in the source provided in the OP. The other crimes have no bearing on the other two charges as far as Trump.
Yes I read the section concerning the campaign finance guilty plea.
Now you do know its not illegal to plead guilty to charges in a plea deal even if the charges can't be supported. This is one of the problems with plea deals.
Jarrett presents this point with this statement from the OP source....."FOX News legal expert and best-selling author Gregg Jarrett UNLOADED on the New York State acting Attorney General Robert Khuzami and the “snot-nosed kids” and “morons” who put together the nonsensical and flimsy accusations against Michael Cohen and targeting Donald Trump."
Now another thing to consider which hasn't been brought up is Trump's name is a brand and as such he or others involved in the brand can take action against things which could effect the brand. Brand protection is not a campaign contribution.