Is the Octogon Mathematical Magazine still accepting paper submissions?
Yes, the Octogon Mathematical Magazine is indeed still in print.
I was advised by the current Editor-in-Chief to send my paper submissions (in LaTeX and PDF formats) via e-mail.
Here are the Rules governing submission to this journal.
(Edit June 13 2020, in response to Nate Eldredge's questions in the comments:  Per an e-mail reply from the current Editor-in-Chief:)

Dear Sir, we reorganized the webpage of Octogon, if we finished you can see the previous issues. Octogon appears two time /year (April and October) printed version. Best regards MB