I'm aware this has been discussed before and seems to be a topic of some ire, but I wanted to give my input on this matter as well.
So I finally managed to link up my old Spiral Knights account to my Steam account (for some reason I always got an error message every time I attempted this before and I never really bothered contacting support about it). I went from 3 achievements (made the Steam SK account for the holiday achievement a few years ago) to 49 in less than a minute as they popped up directly after linking the accounts - great handling on that part, didn't expect my achievements to transfer that easily.
Back when I was actively playing I also managed to score five of the six "Legacy" achievements (only missing the 10k minerals one). Unfortunately, those didn't pop when linking the accounts. Kinda sad, but that's when I started to read into the devs' stance on these achievements.
I can understand the basic notion of only giving those achievements to people who earned them - but as one of those people who managed to gain pretty much all of them, I'm more irked I'll never get a 100% score on Spiral Knights even if I had achieved that last achievement back then.
So if you're completely blocking legacy achievements on Steam now, there's basically no reason not to remove them from there altogether. I'd be okay with that, as they still remain in-game. Also, if there ever *were* a technical option on Steam to keep achievements that do not count towards the completion tally (which there is currently not), it seems the devs should be able to pop those based on the in-game achievements - as is evident by me easily unlocking all my old achievements that I gained while playing with the Java client!
The prospect of being able to 100% Spiral Knights would be something that would at the very least get me playing the game again to hunt for the few achievements I'm still missing. And I know a bunch of people would consider playing Spiral Knights as well if it's something where 100% can finally be obtained. You'd make the game attractive to more people, while the old guard still has their legacy achievements in-game and would have the prospect of having them on Steam again if Valve ever decides to include such an option in their interface.
That's my two Krogmo coins on the issue. Please stay civil in discussing this.
Sorry I want to give my thoughts on this, but I don't know/have not really heard the term? Can you please explain what LA's are? Congrats on linking your steam account! I had issue also.