The Language can be changed in both applications by clicking the "Settings" icon (represented by a gear) located at the bottom-right of the Home screen in Merge Explorer or at the bottom of the Sidebar in Object Viewer.
From there you can tap "Languages" to choose from our list of languages. Give the application time to update to the chosen language onto the app. Languages available are: English (US), English (UK), Spanish, French, Germain, Hindi, Chinese (Simplified), Chinese (Traditional), Japanese, Italian, Russian, Dutch and Portuguese!