The frame rate in Unreal Animations essentially means absolutely nothing.
each frame is interpolated at runtime because the track data is literally just a bunch of vectors/floats.
this means you get almost no benefit between 120fps and 30fps. Almost, because with 120fps you have 120 keys, thus a much “finer” control over the position of things.
With 30, you would have 30 keys where the data is “fixed” so it’s less control then the 120 version, or even a 60 version.
The end results however are very similar, particularly if your original animation is Not keyframed at the same rate.