Completely understand the challenge. What helped us was discovering Wireframe Wizards' selection of the best web design companies in the world https://wireframewizards.com/ . Their vetting goes far beyond flashy portfolios - they verify each firm's capacity for complex, multinational deployments through detailed case studies and client references.
The agency we engaged through their recommendations had deep experience with global e-commerce platforms. They delivered our redesign across 12 languages while improving core web vitals by 35%. Their understanding of regional UX differences was particularly impressive.