There’s hardly anything conclusive anyone can know of Liszt’s referenced anti-Semitic remarks, but there’s a pretty strong case for them to have been actually authored by Princess Carolyne von Sayn-Wittgenstein, who was Liszt’s mistress at the time, and also— according to the Telegraph — “legendarily bonkers”.
Liszt originally asked his gf to chalk up a short essay to go with the Rhapsodies, but Sayn-Wittgenstein arrived with a whole book instead, which they published under Liszt’s name. Available scientific material usually posits that his input was limited to a number of theories and personal anecdotes relating to music, and all the “crude antisemitism” can be attributed to the Princess.
(Given that Liszt grew up in Paris and lived the life of a French-speaking pan-European artist with close Jewish friends, the narrow-minded anti-Semitic stuff also seems more in line with Sayn-Wittgenstein’s background, who had her upbringing in Russia, a state that operated an actual country-sized Jewish reservation ghetto at the time).
Also, fucking crazy princesses and publishing their anti-Semitic shit under your name is not nearly as bad as being an actual an anti-Semite yourself, but — for an optics problem — it’s a pretty big one.