Japan works on RON ???
Methanol 106 RON, 6.5 A/F
Kero 0 RON, 14.5A/F...however Kero spark engines work knock free at 4-5:1 compression, so they DO have a knock rating, same as N-Heptene, the definition of zero.
Kero has no vapour pressure to speak of, methanol some, but not much around freezing.
A/F ratio favours kero, but not methanol.
Typically, 10-15% methanol is about as much as you'd want in petrol/kero etc. for separation issues...a little water makes that hard.
More can be dissolved with acetone or MEK.
Given where you are, and if you have to get somewhere, and damage to the fuel system isn't an issue, and you will be going really slowly, with no harsh acceleration...
I'd mix a small test batch of kero/methanolin the ratio that you've got and see if it separates...then decide my risk profile, what I was prepared to run, for how long...regardless, may need ether to start the engine in winter.
If it was an absolute emergency, I'd run some pretty wild fuel risks...major problems don't occur in minutes...
Just out of leisure, as a late teen, I melted in line fuel filters, cracked fuel pump diaphragms, corroded fuel lines, holed fuel floats with various blends of ethanols, MEK, acetone, diesel, kero, vegetable oil etc...and was rarely stopped by a fuel related issue (Carried diaphragme, screwdrivers and filters as spares).