Working on Hand Sync

Hi, I have encountered two major problems as I practiced hand sync. My first problem is about evenness of notes during meta-chunking challenge from synchronicity seminar, and my second problem is about syncing my left and right hands at high speed. Regarding the first problem, I have recorded myself playing the 19-note challenge in two videos, which were recorded few days apart. When I listened to the 1st video in slow-motion, some of the notes were uneven. I notice that when I accented the first note, I would be making a larger downstroke motion which made my pick moved away from the string further than other non-accented notes. This difference in displacement made the notes sound uneven, creating a "swing" kind of feeling for the first two notes of each chunking group. The reverse of this, i.e. a smaller motion to make the non-accented notes sound lighter to create a more obvious dynamic contrast, would also make me rushed the non-accented notes as the pick stay very close to the string after each stroke. This happened sometimes in the video. My problem was if I accented the first note, unevenness would occur. However, if I do not accented with larger motion, I was simply playing tremolo which made me unable to keep track of the number of notes I played. I ended the challenge two notes earlier at later attempt in this video as I lost track of the chunking due to non-accented groups. My question here is: how should I accent the notes so that no excessive displacement would take place? I continued to practice without finding a solution, and somehow the unevenness issue got better. Though the notes were not perfectly evenly spaced, but it was better than the 1st challenge. Please check the "high speed 19-note challenge 2nd" video. Now I got one more question: does this unevenness issue simply get resolved with more practice? Regarding the second problem,I have also tried to apply this 6-note chunking to an actual licks, which is playing a short licks of 12-8-10-12-10-8 on the same string. However, after incorporating my left hand, my playing just slowed down almost by half compared to playing tremolo and the playing sounded very sloppy. I just wonder what was holding me back and what can I do to play more cleanly?