Does the owner of a hotel booking website bear a sin if foreigners who do not adhere to Islamic dress code or drink alcohol book hotels in Islamic countries through his site, and does the ruling differ if the English version of the website only books in European and American countries?

There is no harm in earning from displaying permissible advertisements. It is also permissible to take a brokerage commission for bringing customers to stay in hotels, unless it is highly probable that the person requesting the reservation intends to engage in unlawful activities. In such a case, assisting them and the earned commission become unlawful. As for someone about whom it is not highly probable that they intend to commit unlawful acts, it is permissible to assist them, and their sin is upon them if they commit a forbidden act. There is no harm in putting an foreign version to attract customers, while avoiding assisting anyone about whom it is highly probable that they intend to commit unlawful acts.