import re
text_source = '''Text [something_id='123'_more-info='321'] Text...'''
search = re.compile(r"\[(something[^]]*)]")
print( search.sub(lambda x: f"{{{x.group(1).replace('_', ' ')}}}", text_source) )
aW1wb3J0IHJlCnRleHRfc291cmNlID0gJycnVGV4dCBbc29tZXRoaW5nX2lkPScxMjMnX21vcmUtaW5mbz0nMzIxJ10gVGV4dC4uLicnJwpzZWFyY2ggPSByZS5jb21waWxlKHIiXFsoc29tZXRoaW5nW15dXSopXSIpCnByaW50KCBzZWFyY2guc3ViKGxhbWJkYSB4OiBmInt7e3guZ3JvdXAoMSkucmVwbGFjZSgnXycsICcgJyl9fX0iLCB0ZXh0X3NvdXJjZSkgKQ==