I appreciate you joining us here again in the Community. After some research, it seems those particular characters (parentheses and colons), null the search results entirely regardless of the text. In the case of your example, searching for Teacher Mary or Father Mary will yield any customer with any combination of those words.
I'd be more than happy to get your feedback on the search index up to the Development Team, I'll just need to clarify the intent. Can you provide me some examples in which you'd like to utilize those searching structures? This information will help me build a request to escalate for you.
Thanks for bringing this matter to my attention, I'll keep an eye out for your response.
Re: Customer/Supplier search does not index words delimited with other than space
I agree that the word in parentheses doesn't matter. A search indexer works by looking for whole words to index. My guess is that Mary is not indexed as a word because your indexing algorithm expects a word to follow a space (or start a line), when in fact a word can also follows a parenthesis or colon (and other non-space delimeters).
In my case I happened to modify the "Display name as" for a customer to add a child's name in parentheses and discovered "John Doe ( Mary )" finds Mary and "John Doe (Mary)" does not. It would be simple enough to update the algorithm. I'm not suggesting this is a big issue, just something that wasn't considered.