Here is a list of achievements that cannot be earned anymore and/or do not appear in the achievements widget anymore.
American Idol 'Hidden Talent'
"Gather X votes."
You earned these badges in the American Idol campaign. Players would stand on the Hot Spot & Scoreboard, to play a song in a room. Users would then use a Voting Chair to rate the player's performance. The more votes you accumulated, the higher badge you would earn. After the New Habbo updates, when music furni was broken, this system was never fixed.
"For playing and winning Snow Storm or for the game of Battle Ball X times."
Level 1 - Win 1. Level 2 - Win 5. Level 3 - Win 20. Level 4 - Win 50. Level 5 - Win 100. Level 6 - Win 160. Level 7 - Win 200. Level 8 - Win 280. Level 9 - Win 360. Level 10 - Win 440.
The habbo student badge was made for Habbos that "completed their confusing newbie experience". The badge was discontinued after the Habbo Guides program was introduced. The guide program was later temporarily discontinued for Guide Bot.
"For inviting X real life friend(s) to Habbo."
You got these badges by inviting your friends to come play Habbo. You could send people an "Invite Link" through Habbo's website. If the invited person created an account through the link, you would earn badges.
"For charging X Pixels into Fireworks Furni."
When Pixels were removed in June 2012, these badges became impossible to earn.