You actually are right, I just found a picture before I touched anything and the hairspring looked decent. It was not an ingenious idea to practice using tweezers on the balance bridge, but I am glad I could handle it better by the end. Nonetheless, it was intended as a practice watch anyway. That hairspring looks to be beyond repair now.
Having now seen the original state of the hairspring, I am actually confused. The watch was running flawlessly for over a year but then one day it died on me. What could have caused this? The thing is it appears to me that the pallet fork moves pretty freely.
@Nucejoe I guess the second picture is what you'd be looking for. I kinda feel ashamed to be here.
I always used Ronsonol lighter fluid, you can leave parts in it for days, providing you have a small container with an air tight lid as it evaporates very quick. No parts that have shellac will be harmed in any way.
You are only drilling out the broken bar not the hole, using a smaller drill if careful will not affect the hole so the angle doesn't come into play. I have in the past done many of these and always had a good result.
Given the relatively small size of the mainsprings, and the relative complexity of the associated gearing, and the large balance, I suspect that the most likely explanation is that they were looking for improved accuracy rather than run time. As you say it looks more like their aim was to reduce isochronism errors. Your freshly cleaned version seems to suggest that this might have been a successful engineering endevour.
Compare with for example the double barrel Seiko spring drive.
"This same elite team of watchmakers now presents Caliber 9R02, a new movement that has two mainsprings set in parallel within a single barrel and uses the unique Torque Return System* to deliver a power reserve of 84 hours."
In that particular caliber the setup of the two springs is some what different. I suspect the increased jewel count in the Seiko might be put to a somewhat more productive use too.
Although the Seiko is arguably not fundamentally that much more accurate.
"A new Spring Drive caliber, 9R31, which has the same dual mainspring structure as 9R02 and the same high precision rate of one second a day and delivers a power reserve of 72 hours."