Customization of icu_transforms

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):

OpenSearch 1.3 (newest)

Describe the issue:

I want to use the ICU library in the AWS-Service OpenSearch Service. More specifically, I want to create a normalizer which does the following normalisations:

Ä > Ae; Ö > Oe; Ü > Ue; ä > ae; ö > oe; ü > ue; Ø > Oe; ø > oe; Ő > Oe; ő > oe;

I have not found a way to configure opensearch in such a way. Is this possible and if yes, how?

Thanks in advance