The goals aren't retroactive at this time. You have to earn them all starting from when the goals was introduced on the older servers.
The good thing about you still being low level is that you can still earn them all.
The hero one once you reach the next goal point you will earn all the past one. IE: Get one of your level 40 heroes to 55 you will get the 35 and 55 Achievement.
If you get your Castle to 12 you will earn the Castle Level 3, Castle Level 5, Castle Level 8, Castle level 10, Castle level 12 Achievements all at once. So you don't need to degrade your building just go forward.
If they add the Castle Level 21 and Castle Level 22 for levels 100 and 105 along with the goals for it. It will enable older players already capped to earn them all.
Formations though they will either need to add 2 new formations or they will need to set that one to retroactive. Because you can't remove the formations but if you don't have all the formations yet you can earn all the goals.