I think they can be useful and interesting, but probably not advisable while you’re continuing to learn foundational phrases (even on the higher end, a la N2 or N1). The way Japanese grammar is taught differs greatfly from the way it’s taught as a foreign language, and at the level of high-school textbooks, what you would be dealing with on the grammar front would be niche analysis designed to provide closer inspection for lifelong native speakers.
That said, texts that are more reading-focused could be a benefit, but so would just reading whatever books interest you.
I’d finish off Kanzen Master, but keep up with other outside reading at the same time. If you’re interested, Japanese language books (on counter words, on keigo, Nihongo Kentei prep, etc.) aimed at a general audience may also have what you’re looking for in a way that’s a little more useful and engaging than jumping into an actual textbook. Though that could be interesting if you think you have all the basics you need out of the way, and it wouldn’t be your main source of learning. But my main advice would just be to pick up a novel, short story collection, etc. But basically no reading is bad, so if your heart is with jumping into a 国語 textbook, do it.