Calendar with fully customizable text or polish language

Hi! Could you recommend some calendar to let users schedule a call (like Calendly), but with fully customizable labels, and buttons? Calendly offers adding custom question, but still - u can’t change some labels manually, and unfortunately they ain’t got my language in options. Website’s target group mostly don’t know english, so I can’t keep it.

Also - language i gotta do it in is polish, so maybe there is some calndar which offers polish?