Keaschall, Lee and Lewis are abysmal players with the glove, but the Twins have used defense extras to spot fix that problem in close games, in the past.
It would be nice if they brought Kreidler up, sent lewis and Keaschall down to St.Paul but that - Might - improve their bats but using Julien as an example , the iron gloves rarely go away.
It took a long time before Julien's gaping whole at Second was removed and as you said, St.Paul has no players better, with the exception of Kreidler, and maybe Culpepper.
In the next month things might change but right now pitching is the major problem so glove work is probably not a big deal on the FO's mind.