Raising your AR fast is no big deal, since there are promotion quests that pop up at specific ARs and you can decide not to do them in order to stay at your current world level in case you feel that your roster is underleveled for how difficult things are. There is also rumored to be a way to temporarily lower your world level that might come in a future version.
At any rate, you'll only have problems if you spread your exp books too thin. Once you have a main team that can reliably handle high level domains and bosses (AR 45+), you can start spreading your resources out.
EDIT: there's also an event coming at some point that doubles the yield of ley line blossoms. I'm assuming it will only double the mora/exp books you get and not the adventurer exp, but we will have to wait to find out.