Re the OP's query about thoughts Re the Casti Magica, or other "high-end" alternatives: The Magica is a drool-worthy instrument to look at and to hear. Same with the Magica CBAs. In my view they are also flabbergastingly expensive. There is also a "Castagnari sound" that some love and some don't care for. It's the same with the Casti bisonroic button boxes. Dunno if it is the hand reeds or the way they engineer the chamber acoustically. They're a bit soft and refined sounding compared to some other makes. Yet there's a bit of a bright chipmunky-sound to the highest notes that some don't like. Not in a shrill way. It's just like a little squirrel or chipmunk on some of the highest notes.
"High-end" alternatives--
-----Well, in Irish and perhaps Scottish, the two-voice MM Saltarelle "Clifden" model is huuuuge in popularity. Note the model name, a lovely town on the Irish West Coast. Very favored. By those who can afford to pay $6K US for an MM 34/60 accordion with no bass register, and think that is fair value, which I do not. I also like a shorter lap-to-chin height for folk music, and the Clifden is even "taller" that way than some other 34-keys. Personally for folk it's 26 or 30 every time for me. You can see a Cliden in stock now at LB in the 60-bass PA section.
-----There is also the Saltarelle "Cleggan," another nod to Ireland. LMM 5-register like the Magica in the original post above. The Salts have a bigger, rounder sound to the softer, yet "pointier" sound of the Castis. It's all subjective taste.
-----Manfrini has also gotten into the act with luscious and lusciously expensive high-end wood-body folk PAs. They are a Scottish concern that contracts with a Castelfidardo maker (I forget which) to their specs. They were offering a two-row Irish box for a while, the "Bosca Ceoil," that was an amazing take on the haunting, often-called "ghostly" sound of the original mid-century Paolo Soprani 2-rows so cherished in Irish trad, while being smaller, lighter, and faster in response. Manfrini offers an MM 35-key and a 4-voice wood-body 37/96. High-end and high-priced.
Manfrini Artisan Piano Accordions - A small production of high quality instruments finished to your own specification. From £3,750.
www.manfriniaccordions.co.uk
-----Petosa offers the "Little Pro XT" 32/96 4-voice, and the "Little Pro," 26/72 3-voice. Arty color combos and painted stains. Those "Swedish blue-steel super-duper a mano" (or whatever) reeds. High-end and high-priced. You can see video demos on the 'tube.
-----Bugari does a fantastic 34/72 LMM that sounds great for trad/roots music, and there's also 37/96 (perhaps 4-voice). They also offer 26/48 and 26/60. Not cheap or anything, but fairly priced compared to the Castagnari/Saltarelle stuff.
Personally, for Irish at the end of the day a PA like a Piatenesi/Ottavianelli or Dino Baffetti 26/60 or 34/72 LMM would be plenty of quality at a lower price than these oh-so-luxe Castagnari or Saltarelle "wood cabinet" examples, if you could find one given the fire at the DB factory and the post-COVID price hikes on everything across the board. Or a vintage Hohner Concerto or West-German Student if you could find one in excellent nick. Or . . . Blasphemy of blasphemies, a brand-new Asian-made Hohner Bravo MM 26/48 or LMM 34/72, or East-German made Weltmeister MM 26/48 or LMM 30-key or 34-key. Or a Czech-made Delicia. They might need a bit of set-up tweaking out of the box, but they are totally playable enough, and sound perfectly fine, for dance-based folk music.