Yep. 16 mains doesn’t tell you where the mains start (or end). The number of grommet holes at the throat is the best indicator of that. Two of the most common examples: 6 grommet holes in the throat bridge calls for starting the mains at the throat, while 8 calls for starting the mains at the head. Where you start (along with the total number of mains) will determine which direction the outside mains run toward (either toward the throat or head), and therefore will dictate where the mains are tied off.
The job itself looks fine other than where the top cross was tied (as
@esgee48 pointed out). Stringing the frame 1pc would have avoided that. Or having the means to hold the top cross (ex. with a starting clamp), would allow stringing the frame 2pc, crosses top down, eventually tying the top cross off on the 3rd cross.