Just had to re-read some previous points but from what you typed, Gustav got the system upgrade feature about 4/5 days ago starting from after he got shot with the energy on the ship. From there 1 night passed and the next day was the knowledge exchange and 2nd day was the fight the 3rd day I believe they returned home so even if it wasn't done upgrading, it would be way more than 34%. Another thing was the system activated to steal Zim's bloodline but it didn't active to take the worm bloodline? And then of course he waited an additional 2 days for it to upgrade? You could probably just change the days required for the upgrade since it isn't a major thing but the bloodline absortion thing seems kinda big. If i'm wrong about this sorry but good story nonetheless :)

I may be late to this story but so far it has been amazing apart from certain points, but this plot-convenience of trying to keep side characters relevant without any real build up will tire fast IF used repeatedly. I can only hope that future chapters don't introduce more side characters, that get deus-ex-machina every time you want to keep them for further use...