As someone who had all crafters to 50 before 2.1 this is painful to read as the only experience available then was actually crafting, levequests and GC turn ins.

Ixali, prior to 50, are great but other than those options, that's it. Thankfully though, you can easily stack xp buffs to quicken your general crafting xp. Challenge Log xp is a weekly benefit, as well as first time completion of any item crafted (even comes with achievements). Food xp buffs, FC crafting buff (if your FC prefers other active buffs you can always use GC Crafting manuals in place of it) and crafting stations at your FC house if your FC owns one.

GC turn ins and levequests double xp rewards for HQ - meaning you'll always want to. It'll save you on levequest expenditure and sky rocket your leveling progress. Back when I cheesed crafting levels with levequests it was only about 5-7 HQ turn ins per 8-10 levels. Unlike how people cheese the crafting levequest system from 60+ you'll want to only use the highest grossing bracket available to you. If your crafter is lv15 and only have lv15 levequests available, find the largest xp payout levequest and spam that sucker with hq turn ins until you unlock the door next bracket.

99 levequests should be more than enough to get at least 3 crafting classes to 50 with proper planning and resources. It'll slow down for everything else afterwards as levequests is the absolute fastest method but if you really wanted to 50 all crafting classes quickly it's easily doable. If anything you'll run out of shards and crystals before anything else in the process.