However, there are exceptions to your list:
早口 はやくち
一口 ひとくち
沢山 たくさん
歳 there are words that break the rule, but those are less used words so I will not list them
高 same as above
綱引き つなひき
寺 quick search didn't show any exceptions, but that was just a quick search.
and so on
But similar conversion happens for many (maybe not all, but many) kana that have "hard" and "soft" version.
For example
島 しま ー> じま