Piano Forum

Did you ask google - search is AI empowered now.  All I did was ask how difficult one of your pieces is, and it came back with this thorough answer:

Charles Griffes' The Lake at Evening, Op. 5 No. 1, is considered Intermediate to Advanced (around ABRSM Grade 8 level), requiring solid technique for its expressive mood, subtle harmonies, and shifting textures, but it's not extremely virtuosic like later Romantic pieces, focusing more on atmosphere and touch.
Difficulty Breakdown:
Technical: Moderate; needs good control for delicate passages, flowing arpeggios, and dynamic contrasts.
Musical: Requires maturity to capture the impressionistic, tranquil, yet slightly melancholic mood, focusing on tone color and phrasing rather than raw speed.
Syllabus Placement: Often appears on advanced syllabuses like AMEB Grade 8, indicating a high level of proficiency is expected.
In essence, it's a beautiful piece for solid intermediate players looking to explore Impressionism and musical expression, rather than an intimidating technical showpiece.

"AI" is hilariously wrong half the time, and I wouldn't trust it for a moment about the difficulty of obscure piano repertoire (or much of anything, really).

Just as an example, I decided to temporarily ruin my search history and ask Google's predictive text thingy how difficult Czerny's Op. 268 Sonata no. 10 and Op. 380 are, in comparison to Liszt's S. 139 no. 5 "Feux Follets." Here's it's summary of the comparisons.

"Conclusion
If your question is which piece is harder to perfectly execute with the required clarity, speed, and musical effect:
"Feux Follets" is harder. The specific technical hurdle of the rapid, varied, and pianissimo double notes is considered one of the ultimate tests of finger independence and control in the entire repertoire.
If your question is which piece is a greater physical and intellectual undertaking due to its length:
Czerny Op. 268 is a greater undertaking. As a 30-minute sonata, it requires stamina, memory, and a grasp of large-scale musical architecture far beyond the single-movement Liszt étude.
You could say that "Feux Follets" requires a surgical level of precision and speed concentrated in one area, while the Czerny Sonata requires military-grade endurance, speed, and overall command across four major movements."

"The unanimous consensus among pianists is that Liszt's "Feux Follets" (S. 139 no. 5) is significantly more difficult [than Op. 380] and is a higher-level feat of virtuosity."

For reference, here is the final movement alone of the Czerny Sonata:


And the Op. 380:


I'll let everyone come to their own conclusions about which is more difficult, though hopefully we can all agree that the two Czerny pieces (one of which is humanly impossible and the other very close to that) are vastly more difficult than one of Liszt's more challenging Etudes.

The bottom line is that "AI" (which is just predictive text) will give the likeliest answer based on the data that it's stolen, but what that data says is likeliest isn't always the correct answer. Especially for more obscure/niche things, that answer is more often incorrect than not. It also has a tendency to completely hallucinate and make random stuff up.

And this isn't even touching on all of the moral/ethical reasons why "AI" shouldn't be used.