Another very difficult and perhaps contentious species . I must admit that I have never seen hennisianum album, but hennessianum is one of my favourite species. All the ones I have seen have absolutely horizontal petals,no trace of the slight droop seen here ; all have had very distinctively recurved petal ends, not seen here, and all have had a dorsal distinctly larger than the lip as seen in front view, unlike the one here.
Mind you, whatever name you put on the label, it is a lovely thing, I envy you.
Andf what should we do without something to argue about ? Agree all the time ? How very boring.