Thanks for your comment!
Did you try the “Slide Mode”? The default mode is “Add Clones Mode”, where you drag to add (or remove) clones (held frames). But you can change the mode to Slide Mode, where you instead are dragging your original (white) drawings up/down through the “sea of clones”. This way you can easily adjust your local timing without destroying (offsetting) your timing later down the timeline.
Find Slide Mode in the X-Sheet menu.
By the way, you can not accidentally change the order of your originals, they will be pushed like carriages on a train.
If you WANT to change the order and, say, move a drawing to somewhere else in the x-sheet – just use cut/paste. Ctrl X while standing on the drawing, go to the new position in time, Ctrl V. Cmd X and Cmd V on Mac.
To adjust the size of your X-Sheet frames (thumbnails), go to the menu X-Sheet -> Thumbnail Size – you can set it to Tiny, Small, Medium or Large. Use the shortcuts Ctrl < or Ctrl > to go smaller or larger respectively. Cmd < or Cmd > on Mac.
If you find you still need more control, please let me know. I am all ears. 😉