Answer: It depends on the regulation that the required disclosure is being made under. For example, under Regulation Z of the Truth in Lending Act (12 CFR 226.27) disclosures made in a language other than English are allowed.
However, according to this regulation, an English translation of the foreign language disclosures must be made available upon a customer's request.
It must be noted, however, that this rule does not apply to sections 226.16 and 226.24 - both of which pertain to advertisements - and require the use of English language disclosures, even if done in conjunction with a foreign language disclosures.
Further, just because an initial disclosure is made in English does not mean that subsequent disclosures also be in English. Thus, Company A can make an initial disclosure in English and then a subsequent disclosure in Spanish- as long as the English language translation is provided upon request.