The international customer base is real
The Marina Alta and wider Costa Blanca have large British, German, Dutch and Scandinavian resident and tourist populations, a Spanish-only site quietly excludes a large share of potential local customers.
Where it matters most
Restaurants, holiday rentals, healthcare, legal and trades businesses see the clearest impact, customers actively search in their own language before booking or buying, and a matching site builds trust immediately.
Doing it properly
Real multilingual SEO means separate, properly translated pages for each language rather than an auto-translate plugin, each language version needs its own keywords, metadata and local search presence to actually rank.