They seem to be doing more and more better with time. They were perched together this morning sleeping. They moved perches during the night from the rope perch to one of the smaller diameter branch perches, but they moved together
Have not heard Charlie being aggressive anymore. I even got to trim their toenails the other day. It was getting to the point where I probably should not wait any longer. I decided to suck it up, be the bad guy, and get the job done. It actually went surprisingly smooth. Of course they both were not too happy with me at first, but eventually each one settled down in my hand and let me clip their nails. Afterwards (and this is of course what I was most nervous about), they immediately went back to being normal happy finches. They didn't hate me. Charlie even came to my hand a few minutes later. Will keep updating as time progresses.