Is there any difference between US convection ovens to ovens used in other parts of the world

Coming again after you guys helped me with my previous issue

A quick summary of the previous question: Bottom of cookies and frozen pizza seem to be almost burned but the top and interior were not fully baked
What the guys told me is that the upper heating element is probably not working and convection is the way to go

I took some action and bought a GE oven model: JB655YK6FS
I tried to have the pizza again and in both times the results were still not good
Instructions on the box are 400F for 18-21 minutes
My attempts with convection:

1. 375F, middle rack [3rd one]
2. 400F, 2nd rack which is closer to the top heating element

On both attempts, I still reached to 25-30 minutes without the cheese to be fully melted
According to the oven’s manual:

The Convection Bake mode is intended for baking on
multiple racks at the same time. This mode uses heat
from the upper and lower elements, along with air
movement from the convection fan to enhance cooking
evenness. Baking time might be slightly longer for
multiple racks than what would be expected for a single
rack. To use this mode press the Convection Bake
pad, enter a temperature, and then press Start. Always
preheat when using this mode. When baking more
delicate foods like cookies and cakes, it is recommended
to reduce the input temperature by 25°F for improved
cooking performance

I called GE in order to understand how their convection is working and they decided to send a technician [because the guys on the phone didn’t know anything!]
The technician made some calls and apparently the upper heating element is not "truly involved" in the baking process
What happens is that the lower element + fan are working through preheat phase and when it is done, fan is working only if sensors detect some issues with temperature and the upper heating element is not really turned on but sort of having small short bursts to help keeping the temperature – it is still used for broil

So my questions are:

1. Is that how convection ovens work in the US in general? Even for other manufacturers?
2. Did I just pick the wrong oven? Do you have any recommendations for other ovens that are more appropriate for my goals [mainly cookiescakes]
3. In Israel we have ovens that work with symbols as described here
   You can see that you can choose to use both elements with and without the fan
   Are you aware of any differences between the way US ovens work comparing to other places in the world? If so, how do you convert 320F & 10 minutes recipe to US convection ovens?

Appreciate the help!