In early 2026, complaints arose from Latin American fans regarding the lack of official Spanish and Portuguese localizations of Undertale and Deltarune. This stemmed from earlier complaints over merchandise producer Fangamer's high shipping costs to Latin American countries, and a lack of South American tour dates for the "Undertale: The Determination Symphony" concert tour, both due to financial and logistical issues on part of Fangamer and the concert organizers.

In response, creator Toby Fox released a statement explaining that the reason why the games' only official translations were in English and Japanese was because he wanted to provide direct oversight to localizers in languages he was already fluent in. Since the games' scripts rely heavily on wordplay, he wanted the translations to adhere as closely as possible to his intended vision to reduce the risk of translation errors, adding that he was "not against official translations for other languages if we could make it work the same way..." Regarding Deltarune specifically, Fox expressed concerns that producing more translations would prolong the game's already drawn-out development, and endorsed unofficial fan translations as a way to allow fans to "interpret the game without the burden of being "officially" perfect". This statement drew mixed responses on social media, with some defending his perfectionist creative vision and efforts to manage the scope of development, while others felt that his standards were unnecessarily high and that the financial success of the games justified the demand for more translations.