[relwin]

Why is the paper's copyright footer "1992 Information Processing Society of Japan" when this work is actually from around 2019?

[ansgri]

Probably used an outdated LaTeX template.

[JohnKemeny]

Not so much outdated as simply not filled in. This is a submitted pdf, not proofed pdf. You can see that both volume and page numbers are missing.

These are things filled in by the journal in the proofing stage (after peer review).

[dang]

Good catch! Based on https://arxiv.org/abs/2009.14336, I put 2020 in the title above.