I don’t think you can search charges or text within them. The documentation lists what search endpoints there are - company, officer, disqualified officer and all (searches those three together):
Also for (some) explanation of how the search works see the announcement (2016!) of the current search facility:
As of the Wednesday 27th July, the following search enhancements will be available:
All search. You are now able to search across Company, Officer and Officer Disqualification with a single search request, through a GET /search request.
Previous company names and other officer name searching. Search now considers a companies previous names, or other names an officer may be appointed as when satisfying the search.
Dissolved company names. Dissolved company names are now considered, but a…
… and also a quick overview of search:
The search is not a simple search through a couple of fields, it is a complex search with parsed search terms against a pre-built index of multiple fields and combinations of fields, utilising partial matching, inverted-indexes, frequency algorithms, cadence, weighted scores, fuzzy matching, stemming, synonyms, company name ending synonyms (English and Welsh), soundex etc. The search does not search our company names and numbers directly, but rather searches multiple INDEXES of the company names…