Is hokku difficult? The simple answer is no.
The only difficulty in hokku comes from what we add to it from our own minds. Really, a hokku is just a meaningful experience of the senses expressed in the context of Nature and the place of humans within Nature, set in the context of the seasons.
One can, of course, find old Japanese hokku that were difficult, because old hokku had not lost its literary connections. So often an old hokku cannot be fully understood without knowing that it used a phrase from this or that Chinese poem, or an allusion to an historical or literary event. I have no interest in such hokku, because they are not hokku at its best. They are just another form of hokku as a game. To some it was a word game, to others a literary game —
“Guess the puzzle.”
What was worthwhile in old hokku was its expression of an experience of one or more of the five senses — seeing, hearing, tasting, touching, and smelling. And there is nothing difficult about that beyond the willingness to give up our “thinking” and attachment to the notion of “self” for a while, and to just go with actual experience.
Yes, one has to learn how to punctuate, one has to learn that a hokku has a “cut” between the shorter and longer parts, one has to learn how to create internal harmony in a hokku, but really these are easy things. It is Nature that does all the work — Nature that creates an experience we feel to be significant.
Some people like to give the impression that hokku is difficult and mysterious, but it is not that at all. The best hokku are straightforward and direct, like this summer verse by Taigi:
A midday nap;
The hand with the fan
That could have been written about most any place in America on a hot day.
Our modern hokku has none of the excessive characteristics that did sometimes make old hokku difficult, because modern hokku takes what was best in old hokku and sets that as the standard. We can cheerfully forget all the rest and leave it to scholars and academics, because it is just the chaff of the history of hokku.