compression cels have a massive inconvenience (in my opinion anyway) in that they dont "buffer" any denominations. IE im storing certus quartz in a compression cel but i want to build with certes quartz blocs, if i request 64 CQ blocs from a terminal i will get... nothing, because once they are inserted back into the network by the molecular assemblers or whatever they get redigested back down to CQ crystals and put into the compression cel
(this example has a decompression module on the network)

i think a new upgrade card for them would work well, a "buffer" card (that has a fixed buffering size of x stacks you can set per denomination).
unlike compression drawers in other mods, it will never "mislead" as to the amounts in the system (to stay inline with the WYSIWYG nature of the ME system)

example: i have a compression cel with 64 certus quartz, and i request 4 certus quartz blocs. those blocs are crafted and pushed back into the network. they get added to the bulk cels buffer, and the system reports having 48 CQ crystals and 4 CQ blocs, however they are all still contained and managed within the bulk cel. if more CQ blocs are pushed into the cel than the buffer size allows (say 1 stack here) then they are digested down into CQ crystals and added to the main bulk storage count as they would normally without the buffering upgrade

making this an upgrade card rather than baking it into the bulk compression card allows for the current behavior to stay the same (as to not brick anything that is designed around the current behavior)

okay so i was trying to make a setup to show what this would be like under the hood as a network but ive found some strange behavior. here the storage bus is set to have +1000 priority, and the compression cel has its cutoff set to be at crystals. its acting like how compression drawer blocs work and i think this might be a bug

https://youtu.be/OVubvrrF7Ag

Either I'm not thinking clearly enough to fully make sense of this issue write-up, or you're completely misunderstanding how the Compression feature works to begin with.

You, as a player, have no need nor reason to request a compressed variant via auto-crafting just to withdraw it from a Bulk Cell; as you showed in your own video, you can just withdraw these already. The auto-crafting functionality is only there to assist in larger jobs which require those variants in any intermediate steps.

You're also not generally meant to mix different storage media for that same resource—if you're storing an item on a Bulk Cell, the assumption is that you'd be storing it only on the Bulk Cell, without needing anything else. A Bulk Cell is already effectively a bottomless pit, and you can fit an entirely unlimited amount of that item onto one. This is for good reason, and what's happening in your video isn't a bug; Bulk Cells already have full insertion priority for whatever it is they are already storing, and you are effectively moving everything from the barrel behind the storage bus into that Bulk Cell. All of this is already explained in-game, in AE2's own guide, under a dedicated section.

With all this being said, I fail to see the need for such an upgrade card. With or without a buffer, you would still be (and still are!) able to withdraw any amount of a variant item through an ME Terminal, as long as you have enough of the smallest variant to compress into that.

i recorded this to show what i meant by stuff getting reinserted and digested into the network after crafting and you can see me get jumpscared by being able to pull out the blocs using the mousewheel at the end. i dont know if its because of the "craft +" icon & not being able to single click (but other clicks are fine) or if im just illiterate but i dont think this functionality is ever stated and i never assumed you could do that
https://youtu.be/BII45I47ySA

i def think all the technical and nuance details on the bulk & compression card page should be moved to its own page. idk, i might open a seperate issue about the naming & documentation surrounding bulk cels & its cohorts as i think it needs a lot of polishing.

i recorded this to show what i meant by stuff getting reinserted and digested into the network after crafting

This is by design, but it's also not something you'd need to be that concerned about as a player. In simple terms, though, Bulk Cells internally don't "store" anything that isn't the smallest "base" item anyway. Any item that does happen to be of a higher variant just gets "decompressed" into that smallest base item since that is all that the bulk cell is designed to track. The logic for reporting those different item variants to the wider network happens separately to the storage logic of the cell itself.

you can see me get jumpscared by being able to pull out the blocs using the mousewheel at the end. i dont know if its because of the "craft +" icon & not being able to single click (but other clicks are fine) or if im just illiterate but i dont think this functionality is ever stated and i never assumed you could do that

AE2 itself takes precedence when responding to single clicks based on whether an item already exists in storage, but shift-clicking and scrolling should work just fine to bypass the crafting screen response. Admittedly, there are other few things I want to address about the extraction logic there, but I simply haven't had the time to do so, and some of these changes would require changes made upstream to AE2 itself to work as effectively as possible.

i def think all the technical and nuance details on the bulk & compression card page should be moved to its own page. idk, i might open a seperate issue about the naming & documentation surrounding bulk cels & its cohorts as i think it needs a lot of polishing.

If there are issues with the wording or if there is some of this information missing from that page in AE2's in-game guidebook, then I'm happy for you to let me know in a new issue and pinpoint these specific sections that I may need to take a look at again to address.