My initial thoughts
3 years is short turn around for a multi year - we saw this with the Kilt of Dungeonbane. That year the kilt had extra fleece tossed into the transmute and it still ended up being produced in extreme quantities. There are 6(!!) 3 years all listed. That's going to be one heck of a TG crunch and a big power spike all at once.
2 Arcanum set items in parallel to be completed at the same 3 year time span is not my favorite either. If one is going to act as a ticket for the next TD convention in Carbondale, why not let the other be 4 or 5 years long to ease the TG crunch and spread out how fast Aracanum items accumulate.
I see 2 familiars in a new slot? What is special about familiars that they need their own slot? Why not simplify things by using the FoP slot or Spirit Pet slot?
If I follow the "any 4" logic, that means that 4 codexes can be transmuted to make 1 familiar. At the same time, the codexs all grant +2 to an attribute. I feel like that implies we should get 2 - one for the attribute bonus and one to transmute.
I'm a little concerned about the Homunculus from a chaser standpoint, depending on the exact details of the ratio of chaser bits in treasure. These will be SUPER in demand for 6th level cards if it's the only way to get 6th level. I'd almost recommend making 6th level a bonus option if you are equipping 5 piece eldrich or 5 piece arcanum + another level booster.
My suggestions, if you're looking for suggested changes, here are mine in roughly the order of priority I see:
1) Spread out the transmute windows. Ex:
-Let the Arcanum Ioun Stone be the ticket to TD Con 2029 and the codexes be the special event tickets to TD Con 2029. Keep these at 3 years.
-Let the 2k multi year and Monster Bit tokens be 4 years. This can still make the the same transmutes, but now they don't line up with the Arcanum Ioun stone.
-let the UR transmute be 5 years. This can still make an Arcanum Mask, and you could even slightly juice the power or make it more like the arcanum shirt (+2 str, dex, con, focus, and something else).
2) Drop the +2 attribute on the codexs OR create the tome slot (and retroactively add tomes like has been discussed before).
If you're allowing for flexibility in transmute, IMO, they don't need slotless powers.
3) Cat items:
- The shirt and gloves aren't all that great compared to a UR in a set. For example, the Cat's shirt is one of multiple "if you die" items, and those generally don't tend to be that powerful or in demand (see also, butterfly cloak). This could, instead, be a slight increase to one of the Arcanum shirt ingredients, such as a flat +3 str shirt
-Expanded crit range on the melee gloves can be nice, but who is the target audience? 19-20 crit range for melee is pretty common at this point for classes that want it. If we stick with the theme of slightly upgrading an old token, AND it's going to be cat related, Maybe just tweak Gloves of the Cutpurse and make it a flat +5 dex?