Well, one thing immediately comes to mind here, that being that if you're scared of certain knobs, you picked the wrong instrument to play. All of us have to manually tune VCOs (and lots of other things) quite often, so you'll pardon me if I don't see a problem here.
Now, if you need to get pitchmatching between the Digitakt and the modular, I'd suggest the following:
Create a sample for the Digitakt that's nothing but a sine tone at 440 Hz. This then gives you a loop for tuning the synth to the same tuning standard as the Digitakt. However, your samples ALSO need to be tuned so that they comply with that same Concert A, which might be a bit fussy but once you've got it done, you won't have to do it again.
Anyway, once the samples conform to that Concert A tuning and then you use the loop to pitchmatch the synth to the Digitakt, you're then in tune. Given that the Plaits is a digital VCO, it shouldn't drift, so that same Concert A should apply across an entire set.
Basically, this is a simplified version of what I've done every time I've played live, although I use a digital synth's Concert A reference rather than a sample loop, and I'm also usually dealing with anywhere from 8-12 synths and other electronic instruments with those gigs. Even so, it only takes me about 4-5 minutes out of sound check to get the entire rig for a given concert work in tune. But given that I've done pieces that require all sorts of Concert A tunings from 415 Hz (baroque A) to 447 Hz (majorly up-tuned A, sometimes done by me to "brighten" a work overall) and this method works every time, it's worth doing.
HOWEVER...
Getting back to that first point: if you're at odds with the idea of adjusting a certain knob while working, I would strongly suggest that you adjust the HELL out of it instead. For one thing, this will get you used to hearing when things ARE out of tune, and let you practice spot-tuning when needed (which is a pretty invaluable skill in electronic music!). But secondly, it'll help you get out of the corner you're painting yourself into; no synthesist should ever have ANY trepidation about needing to adjust ANY control at ANY time. And besides, have you actually tried seeing what "out of tune" actually sounds like? Fact is, it might actually work...look at Aphex Twin's work, for example. Quite often, he doesn't even use 12-note scales, opting instead for microtonality lots of times. In other cases, he'll let things deliberately detune for musical effect. Take "180dB" off of "Syro", for example...three synths that pretty much NO ONE on here has the money for (Korg PS-3300s...and I'm not lying there, as he's using about $80-100k worth of vintage Korgs in this case), all being sequenced by (or something very much like) a TB-303 for what has to be the most expensive ACIEED track in music history...but he lets the Korgs go out of tune with each other, and the result sounds weird and wild and seriously messed up because of the out-of-tuneness coupled with the rigid 303-type sequencing. Just a thought...