I wouldn't class those two entries anywhere near the same. 1. Dilly dilly shilly shally is not an idiom. 2. It's a totally made up phrase - and also totally nonsensical. 3. It isn't used anywhere by anyone. 4. It also didn't fit the original Japanese meaning at all.
If there had been a consensus that this wasn't used in America, I'd have added it to the option list. But it's definitely known in parts of America - and it's an established idiom from the 1800s. In my view removing this because a number of people haven't heard of it will lead to numerous other changes - all of which will dilute the localization for very little gain. This isn't a main character using this phrase - it's a disgruntled town NPC.
@WatashiWaZero
Materia is both plural and singular. Like diamond.
None of those are errors. They're perfectly acceptable English / grammar, apart from "1000-year-old", which you may have a point on.
Moreover, I don't need any grammar check (unless the sentence is broken, like "Hi, what are for you doing"). There's going to be a lot of changes to it as I walk through the game finalizing part by part. I only need spelling mistakes or words that do not work in US because of differences to Britain. I appreciate the desire for everyone to help, but the vast majority of the bug reports in the last few pages have been localization choices—most of them discussed at length beforehand.
Also note that characters do not need to use perfect English. In every day life, our speech is even worse. No-one uses "that" to join words all the time. In fact, it's omitted most of the time unless a person is being very formal.