Some official sources don't cap it, e.g. this one. And MOS:CAPS is not just about titles, but also about capitalization in article text. These discussions suggest a general consensus to use lowercase on such things, not just in titles: Talk:T1 Light Tank#Requested move 19 February 2024, Talk:Heavy Tank M6#Requested move 21 February 2024, Talk:A7 Medium Tank#Requested move 22 February 2024. Dicklyon (talk) 09:54, 15 March 2024 (UTC)__DTREPLYBUTTONSCONTENT__-->__DTELLIPSISBUTTON__{"threadItem":{"timestamp":"20240315095400","author":"Dicklyon","type":"comment","level":1,"id":"c-Dicklyon-20240315095400-That_light_tank","replies":[]}}-->
As you correctly point out in one of your edit summaries, there is a known bug with using references with list-defined footnotes, as seen here. It is even mentioned on the efn template page – Note: Due to limitations in the MediaWiki software, do not use list-defined footnotes that contain references. The only solution I know of to use footnotes with references is to insert the notes directly into the body of the article. If you know of a better solution that works, please consider posting it on Template talk:Efn. Isaidnoway (talk) 05:27, 21 March 2024 (UTC)__DTREPLYBUTTONSCONTENT__-->__DTELLIPSISBUTTON__{"threadItem":{"timestamp":"20240321052700","author":"Isaidnoway","type":"comment","level":1,"id":"c-Isaidnoway-20240321052700-Battle_of_Kursk","replies":[]}}-->