“Find and Replace” - “Find” restricted to the place between the brackets?

I downloaded a deck from Ankiweb which contains IPA errors in the field Transcription and in the field Keyword: for example every sign “∫” is shown as a capital letter “S”, every sign “ε:” is shown as a capital letter “E:” and there are about 10 other IPA errors like that.
I managed to make corrections in the field Transcription with the help of “Find and Replace” (Browsing - Anki Manual).

But I don’t know how to make corrections in the field Keyword. There are not only IPA signs within these brackets but also normal letters like “s, S” or “e, E”, they would be replaced as well.
I suppose “Find” of “Find and Replace” for this field should be restricted to the place between the brackets of the IPA: […].

Is it possible to set such a restriction?

Any help would be much appreciated.

The following changes [hello] world into [hellO] world:

Find: (\[.*?)o(.*?\])
Replace with: ${1}O${2}

It can only do one replacement at a time, so if the character appears multiple times inside the brackets, you’ll need to run it multiple times.

@dae
Thank you, I will try it.

Applies the same to “Find and Replace”?

Sorry, I don’t understand the question.

dae,
I meant: Applies the same to “Find and Replace” without regular expressions?
If I use “Find and Replace” without such regular expressions, just in a normal way, do I have to run it multiple times, if the character appears multiple times inside the field?
If I have the capital letter “S” instead of the IPA sign “∫” multiple times in the field Transcription, for example.

Nope, the need to run multiple times in the example I provided is just because of the way the regex is constructed.