This is not only an "unusual" but I would say a "wrong" use of "expectancy" in English. The entire text should be using "expectation" here, not "expectancy".
To me, "expectation" is more goal-oriented: it's about that thing you expect. "Expectancy" is a state you are in, namely, that state of expecting something, irrespective of what your goal (expectation) happens to be.
Here is a contrived example (nobody would say this in reality) to illustrate the difference:
"Kate Middleton is in a state of expectancy; her expectation is a future sovereign."
And a footnote: Prior to the late 1960s in the U.S., the word "pregnant" was considered a bit too risque for polite conversation, not quite vulgar, but deserving of a euphemism, as all bodily functions were. So, people would say of someone, "She is expecting," meaning, "She is pregnant." In no other sentence in AE that I am aware of could you use "expecting" without a direct object, other than this one case.