There's no such thing as "a hiragana".
That means “Which kanji became which hiragana?” If there’s no such thing as ‘a hiragana’ that wouldn’t make sense.
As for kanji, “この漢字” also shows up all the time when referring to a specific character. References to specific amount of kanji are everywhere too, eg the “100 Kanji” here. https://www.kinokuniya.co.jp/f/dsg-08-EK-1085796
No, it doesn't. It means "Which kanji characters became which hiragana characters".
Words do not directly translate between languages the way you think.
It’s ok in English to say ‘I love the shinkansen in Japan’ or ‘I love that one shinkansen, which was it… oh the Nozomi.’ Because shinkansen is meant to he specifically Japanese and isn’t integrated into English, ‘I love shinkansens’ sounds clunky, and, sure, many would opt for ‘shinkansen trains’ or ‘Japanese bullet trains’ or something. But none of them are wrong.
Loan words in English are often moving between or straddling various levels of integration.‘Toyota’ is integrated to where ‘Toyotas’ is common. ‘Sukoshi’ comes in as a clumsy loanword with American specific use and pronunciation, i.e. ‘skotch.’ Pronouncing ‘karate’ correctly makes you look pretentious similarly to how saying ‘fillet’ the way Americans do sounds pretentious to Brits who don’t leave off the t.
Further, it’s incredibly rude and condescending to assume you know what I think about how translation works.