Why is one in Russia such a scandal?
because Cohen and Sater had a conversation about offering Putin a Penthouse Suit in the proposed building
the thought process, such a move would have the affect of other Russian Oligarchs wanting purchase suits in the same building as Putin
there is some unfounded supposition this was
1) a Bribe and therefor illegal
[no one has offered ANY Information that Putin was or could have been involved with the project]
[also Cohen not knowing whom else to contact initially sent an email to Putin's Press Secretary IIRC, asking for assistance]
2) Trump was taking care of his Pal Putin, and now subject to blackmail by Putin vis-à-vis giving Putin a penthouse suit
Common Cause and CREW both have lawsuits against Trump, somehow Trump is under foreign influence [Chinese and Russian] because both lease or rent units in various Trump Towers and as such there is also an implication of money laundering via rent payments - which Elijah C will be investigating in 2019]