I think you're right in that there needs to be enforcement provisions, and maybe Trump should be doing a better job of convincing Ukraine that he intends to provide for those. But I don't think it's necessarily a given that the Russians won't agree to any provisions; they'll say that for the sake of bargaining but if they really meant that they wouldn't be coming to the negotiating table. But even if the Russians really aren't ready to agree to security provisions, coming to the negotiating table does not obligate either side to agree to a deal.
I personally would be much more satisfied with my tax dollars going to Ukraine if they had demonstrated that there is no nonviolent solution to this conflict; from the perspective of Americans this is just another case of two countries squabbling over adjoining territories and that's fairly common among countries that don't have a SoFA or defense pact with America (which, regardless of how passionate the Europeans are about Russia pushing into the frontier of western Europe, currently includes Ukraine).
I personally would be much more satisfied with my tax dollars going to Ukraine if they had demonstrated that there is no nonviolent solution to this conflict; from the perspective of Americans this is just another case of two countries squabbling over adjoining territories and that's fairly common among countries that don't have a SoFA or defense pact with America (which, regardless of how passionate the Europeans are about Russia pushing into the frontier of western Europe, currently includes Ukraine).