The fact that they were offering tours of the line, means that there is something worth seeing.
54,000 per year - approximately 1,000 per week, 7 days 2 x 8 hour shifts = about 9 per hour.
54,000 per year approximately equals Sparks 2170 production.
Given the timing of the event, and the fact that a line tour was included, I doubt that the line has been running long.
If they are only doing 3 per day, then some stations on the line are not currently operational.
The only thing that would count against Sparks is workforce issues, otherwise the batteries and motors are made onsite, it is a good place to build the Semi,
100 by the end of the year is only 3 per day, there may be some hold up on parts/staff otherwise it is just a matter of ramping the line,.