The phrase "a difficult matter to" is correct and usable in written English.
It can be used when discussing a topic or issue that is challenging or complex to address or resolve.
Example: "Addressing climate change is a difficult matter to navigate due to the various political and economic factors involved."
Alternatives: "a challenging issue to" or "a complex problem to".
In practical situations it is necessary to obtain the expression of the Green's function, which is, in general, a difficult matter to deal with.
It has been a difficult matter to decide what types of problems really require modelling and solution either with type-1 or type-2 fuzzy approach.
If this be true, were it not then a difficult matter to make a bridge, a civic auditorium, a stadium, or even a hospital, symbolical?
In submitting his expenses on 29 June, chief bailiff F. Bagge noted "We have no power of pressing a cart for the purpose, and 'tis a difficult matter to get one, people feel's so much upon the occasion".
It's a terribly difficult matter to work out.
It can be an incredibly difficult matter to face, but Jazz credits her family with giving her the strength to always stand in her truth.
I was very much impressed by the fact that it is an extremely difficult matter to keep the records of patients who are under observation for some time in a manner so that an intelligent and comprehensive résumé of the patient's progress from the time he enters the hospital until he is dismissed cured, improved, unimproved, or still under observation, can be made.
The essence of Bob's legacy as a colleague and friend is the most difficult matter to capture here.
It is another — and often very difficult — matter to conclude that "this will work there".
An effort to overhaul the nation's election system stalled in the Senate today in a dispute that exposed the raw politics that have long made changing the system a difficult matter: how to curb fraud at the polls without disenfranchising voters.
At the same time, creating a dictionary with a high degree of coverage is a difficult matter due to the continuous discovery of novel compounds.
