Lenient MUX and Load Signal
I am not sure about the 'lenient' part, but for the "load signal", you've misinterpreted the sense of "load".

In this case it doesn't mean "electrical load" or "resistive load" -- rather it is "the signal that 'loads' the value of D into the memory."



Taking a shot at 'lenient': this may mean that it does not have oscillation problems between the input and the output when connecting it this way. A bad situation would develop if during a transition there is enough delay and enough gain between the input and output that a self-sustaining oscillation develops. But it is not a term I'm familiar with in this context.