Here's a very funny notice from a 1928 issue of Beis Va'ad Le-chachomim:
As you can see, it suggests retiring the most famous works by Yehuda Leib Ben Ze'ev, who was one of the Me'assfim, and part of Mendelssohn's circle. As a great hebraist, the works mentioned here were hugely popular in eastern Europe, giving the keys to the Hebrew language and grammar to many generations. The footnote (citing Lev Ha-ivri) claims that he wrote תלמוד לשון עברי on shabbos, never married and died on the toilet!
For an earlier list of books one ought not read, see here, same publication.
(Since I can't resist mentioning Shadal, the Jewish advocacy for the utility of Syriac for plumbing the depths of Aramaic, and therefore Hebrew, is often attributed to him. But he himself attributed the inspiration for the idea to Ben Ze'ev, although it was Shadal who first mastered Syriac and showed how it could be useful. See Ohev Ger (2nd ed. pg. 93):
This was called to my attention in the course of reading Rubin's translation of Shadal's Prolegomeni. Shadal mentions Giuda Löwe ben Zeev here.)
Speaking of Syriac, Here is R. Isser Zalman Meltzer, Even Ha-azel vol. vi Korbonot 1.8, pg. 2, quoting Kohut:
Verily, the line of progress that made this passage possible begins among Jews with Ben Ze'ev, goes through Shadal, to Kohut, and then to R. Isser Zalman.)