I'd like a second opinion: Did my dentist mess up my masseter Botox by injecting too high? (Photos)

Unfortunately, the photos are not helpful. What I can say is that I have been injecting masseter muscles for quite a few years for muscle hypertrophy and TMJ and bruxism problems and for Asian women desiring a more tapered lower face, and the typical three locations for the injections are within the body of the masseter muscle, usually two injections below a line drawn from the angle of the mouth to the tragus of the ear and equally spaced from each other and a third--a single injection--along the jawline. The three injections essentially form a triangle with the apex at or near the jawline. Depending upon the strength of the masseters, the total number of units may vary from 20 to t30 up to 40 units per side. An additional temple injection is not typically done in most cases. You would be wise to contact your injector. Best of luck.

I will start with a short answer. Looking at your pictures and assuming you were trying to smile the same, it is most likely that your risorius muscles were injected. Maybe part of the zygomaticus major muscle was affected as well.
Typically to achieve a full effect of face slimming (muscle atrophy), 10-12 weeks is required.
Unfortunately, your side effects will also taper over 2-3 months.
It is true that there are various bellies of the masseter muscles, such as deep vs superficial. An injector should be assessing the optimal location injection to achieve the result that you desire. Unfortunately, many injectors are simply taught the "paint by number" method over a short seminar.
The hairline injection sounds like your injector is also trying to treat the temporalis muscle. Again, a single point is not very ideal since the muscle is a wide and strong muscle.
I would highly recommend you receive future treatments from someone that is actually knowledgeable on this topic.