First of all, I'd suggest that you take a deep breath and step back (or out of) "panic mode". It doesn't help in any way, but can cause you to react with emotions, rather than with patient discernment. I am not stating this because you are a female, I am stating this as it applies for both genders.
Thus far, the work looks good (from the pics). It appears it was done the way the product "used to be" installed, prior to Hardie's recent change (as outlined on their site - installation instructions).
- As stated, the main concern about caulking the butt seams revolves around the colorplus, or factory pre-painted hardie planks and the color matched caulking. The issue is that the caulking fades to a lighter color over time and stands out visibly when that happens. So this is an esthetic point to review and discuss with the Supervisor.
- Please understand, that it is not unusual for a Supervisor to appear on a job from time-to-time to check on the work and and review any worksite questions or concerns. That is what "Supervisors" do = they are not the "foreman" (that person is on the job at all times). Please do not confuse the two positions, or what their job is.
- As also stated, the question is whether they flashed the backsides of the butt seams. Mention this to the Supervisor, and if needed, get something certified in writing, that it was done, if they (he) verbally states that it was done.
Realize that on a major project, such as an addition, or renovation = you don't know if the insulation, structural framing, beams, electrical, etc, etc - is being done properly, or according to what is necessary, or required by code. That doesn't mean that you should distrust or question every detail of such work.
Take one step at a time. You are jumping way ahead before getting "all" the facts and answers.
Get ALL the facts first by asking educated questions, documenting answers (or getting them in writing). Then go to the next step.
My final advice is to approach everything with a professional composure and stay away from the "panic mode".