Minor change; I've tweaked it to have Craft Points equal to 2 x Engineer Level + Intelligence modifier. So: 12 + Int Craft points instead of 6.My issue with your version is that it has a inventions known, which I dislike because I like that the engineer can adjust from day to day. I'll let you address that before I put up more stuff.
This is limitation is, however, intentional.
1: The Crafting Engineer has no restriction on the number of inventions they can make.
In order to prepare from day to day, they can spend downtime to craft new materials. At hourly rates of progress, they should be able to squeeze in two or more inventions a day in the time they're getting ready for bed, or taking turns at watch, or are an elf and get four hours extra just for crafting.
Thusly the Crafting Engineer can adjust from day to day by making different selections from their inventions known in any combination. Facing trolls? Make a lot of Unstable Bases. Expecting a rough combat? Load up on Healing stuff. Fighting spellcasters? Make more itchisticks.
Wizards, outside of the theoretical, do not have infinite spells to choose from, they have spells known and choose those which to use. With ten known inventions on top of their pre-existent utility, they have more scope to change their abilities for the following day than any other non-mage class (who themselves are less changing themselves, more having a bigger pool to choose from in the first place).
If a mage uses five fireballs at midnight, they don't get new spells unless they rest for eight solid hours, then prepped spells. If they use five fireballs and six magic missiles, then eight hours later they get all eleven back.
If a Crafting Engineer uses five Pocket Bombards and then spends an hour downtime, they get one Pocket Bombard back. Eight hours rest, assuming two hours downtime not spent sleeping? They only get two back.
An Engineer who novas an entire inventory of expendables will have a bit longer to recover than a mage, but they do not need to rest to do so.
An Engineer who invests heavily into reusable items, and will get that benefit all day long without expending a thing.
With Repurpose the Engineer can change a prepared invention into something else on the fly. With Improvisation, they basically have an anyspell effect they can access once a day.
3: Variety Again.
Why does every Engineer know every possible "invention" ever? What ultimate difference is there between two different engineers when they've neither of them got anything the other can't do?
Thematically, Engineers are inventors, that means they come up with things, which in turn means that they must have things that other inventors do not. With a limited number of inventions they know, each of those inventions (short of retraining) is unique to them.