Well I can't even get answer as to whether the 18 tracks line up or not. My guess it that it is multiple dumps into Sonar. If so there will probably be lots of snips and I believe he will have to line up the grid to some track or other. That would put him most of the way there and give him a good visual reference.
 
Back in the day, I transferred many 16 and 24 track tapes with only 4 convertor channels. All grades of problems if there was no sync and the devices were running wild. That's is exactly how I learned to never try to have a DAW reliably sync to external TC. But I suppose it native to nearly everything now.
 
For sure what he's wanting to do can be done a couple ways but I guess he missed his deadline.