Being back in here for something else today, occurred that @AmberV 's request to make identifiable bugs evident on the new forum should get another.
Regular expressions are very useful indeed for those unusual searches and replaces that can very much streamline getting some text in shape.
The problem I’ve most noticed on Scrivener iOS is that replacement using character codes doesn’t function – nothing happens.
An evident example is with trying to put in additional paragraph separators (\n) when the paragraphs are jammed together, possibly from being copied that way from another source.
You should be able to select on RE ‘\n’, and replace it with ‘\n\n’, each in its blank on Scrivener, naturally without the quotes. Using Replace All should clean up any length of text – voila.
What actually happens is that the \n newlines that did exist will be replaced with nothing, so that you get the paragraphs all jammed together and must hope for an Undo.
This is the big one, probably, but if it’s fixed, that probably means the RE library is now called correctly, and so all REs in the fashion of Apple’s version should work.
It would be well for completeness, though, to have a few interesting cases to test this success – for example that capture groups and their ability to copy text into a new place in a replace result also works. This would be very useful for reformatting labeled items, for example.