Please notice that our setup pricing can be found on the pricing page
For a site in English, with an automatic live translation (GDTranslate), a keyword search with Solr, Elasticsearch, OpenSearch, or Algolia, would not be possible. Especially if you need to reach more countries and languages.
You would rather use a vector search like Weaviate, which was successful for WooCommerce clients in a context of multi-lingual queries for a mono-language WordPress.
The vector search will also bring semantic search and automatic check-spelling, with faceting, in 100+ languages.
The vector search and keyword search will be equally fast and scalable. But the overall speed will depend on WordPress mostly: a fast search with a slow WordPress will remain slow, but the search will use less server resources even in periods of high traffic.