I'm unsure where to go this summer/autumn. Among my options would be to join an organised trek somewhere I wouldn't (currently) want to go independently (such as for experience, language, cultural, or political reasons).
Are there any targeted search engines where I can search for organised treks based on criteria such as location, length, difficulty, group size, language, price, and other characteristics? For example, one could search for "challenging tent trekking 7-20 days in northern Russia in August or September with group speaking English, Dutch, German, or Swedish", or "easy-moderate Dutch-speaking hostel to hostel trekking of any duration with luggage transport in northern Spain between September and December". I'm aware of quite a few (commercial or not-for-profit) organisations selling trekking vacations but the market does not appear very transparent. Google Search may miss quite a lot.
Note that this is different from "how to look for a trail buddy"; this question is about organised treks sold by commercial companies or not-for-profit organisations.