My understanding of Qualcomm's frequency band support is the same as yours - 6 bands only.
So I can see where you are coming from when the total number of bands supported by the modem is 7 - so which one is missing??

BTW the 7 are:
800
850
900
1800
1900
2100
2600

What is needed is access to te service menu to find which frequencies are available or more specifically which one is dormant.

To date I have been unable to access this data even though the Service Code is *#0011#
This will give you the LTE band currently in use, but not a list of others available.

My suggestion to use a MiFi unit in Japan is to get around the difficulties that you are facing.

I am sure as a regular visitor to Japan you are aware of other options, but in case ou haven't seen this site, here is the link:
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