With the incoming changes to scrips, I feel the reason why collectible numbers were implemented may have been to prevent people from easily capping their weekly scrips. However since it's no longer the case coming into 4.0, why not allow us to stack collectibles through a GRADE system. F-D-C-B-A-S-SS-SSS which could relate to

F=25%-30%
D=31-35%
C=36-40%
B=41-50%
A=51-65%
S=66-80%
SS=81-99%
SSS=100%

With this you would reduce the number of collectibles from a random assortment of non-stackables to 8 different forms of stackables. 8 so that Aetherial Reduction would still be easy to distinguish based on the grade of the collectible.

If the issue is then, "What about later on when players could just spam scrips with ease to get the latest item." Then why not have it where a specific grade of item crafted/gathered is needed in order to obtain the new items on top of a scrip cost?