I really like the idea of this! I think it'd be better to have a non resetable title (or border/avatar). Would be a shame you're only missing one card and the next login it suddenly says "Missing 36 cards".
I'm more thinking of a specific target for the achievement, like:
- Original Collector (collected 154 cards)
- Grand Collector (collected 154 cards and the premiums)
- Skellige's Pride (collected 31 cards cards of faction Skellige)
- <insert other factions>
Once new cards are added, it can be something like Skellige's Pride II (collected 36 Skellige cards)
And maybe ranks for the total cards, like: Card Collector XI (collected 196 cards)
Every milestone (100, 150, 200, ... cards) adds a border or something.