1. the series malmstones appear to have vanished from existence, which contradicted a lot of what Yoshi P said in live letter, etc: https://forum.square-enix.com/ffxiv/...ards-vanish-to

So, if you're referring to the frame kits that were on the series 1 malmstones track, it looks like those have vanished into the aether and you're screwed like me.

2. if you're talking about the achievement from max rank reached in the series overall, you should be able to talk to an NPC by the board outside at the wolve's den pier to claim your rewards. I did that and received mine there. At least, I assume I received it. He congratulated me, but I never looked at my adventure plate interface. My spouse did this and got their achievement frames that way; they just confirmed.