Some people have probably already figured this out, but I did just verify this. My CRP is 70 so I made a collectable for Zhloe weekly then changed to ALC which is only 62 and turned it in successfully for experience on ALC. It really doesn't keep track of what craft you made the general collectable with, just what quality it is and which craft job you are currently set to. I also verified the weekly challenge for melding materia functions the same way. I melded onto a arcanist book (removed 2) then melded again to hit 5 but made sure I did it with ARM job on and got the achievement xp on ARM. Have a good time taking advantage of the "loophole" in the game crafting system.
*Also the weekly crafting challenge for 20HQ and 30NQ crafting items gives a % of the required xp for that level, so make sure you are on a non-maxed job when it is about to trigger for the xp if you have one.
I haven't checked the Kurenai, but would expect a similar situation if they ask for general craftables.
*Note: I noticed on the turn in that the xp varies a bit depending on job level vs crafting level, so if you are using it for xp you might cycle through and see which gives the best return.