Harpsichords have been somewhat of a thing in Visual Kei since the origin of TanbiKei (Vkei bands that have European themes like Malice Mizer or Versailles).
Malice Mizer was pretty well known for using harpsichords and other European instruments in order to fit with their Baroque theme (GackT era) or Victorian theme (Klaha era).
I wouldn't say it's a trend but more of a recurring theme that pops up every so often, since lots of bands today are still heavilly inspired by Malice Mizer, Versailles, Lareine, Moi dix Mois, etc.
My favourite example would be it's use in Vasalla's Yurikago.
However, the band most notable for Harpsichords is Moi dix Mois. Almost every song they make uses an organ, orchestra, or harpsichord.