Hi Andy,
I think the translation that you have for the tag is accurate:
広島県 – Hiroshima Ken - Hiroshima Prefecture
佐伯郡 - Saeki Gun - Saeki district
官島町 – Miyajima Machi - Miyajima town
一四六 – 146
海軍大佐 – Kaigun Daisa (Navy Colonel)
松井島吉 – Matsui Shimakichi (Given name)
I don't know anything about Japanese Navy ranks, however, when I put "Daisa" into the online dictionary that I use, the definition comes back as "colonel; (navy) captain" so it might just be a semantic thing. https://jisho.org/search/daisa
That said, how convinced are you that the surrender tag is genuine? It looks practically pristine and the ink is so black it could have been written yesterday...