I am able to replace what you are seeing in the browser by deselecting 'English' from my list of languages in the settings, and then clicking 'save':
As I understand it, the way it works is that when you deselect a language you will not see content that was explicitly set to that language.
So, it looks to me like your Jerboa is set to a language different than English. The strange thing is that you do see the content in the browser, so your settings do seem to include English. One guess is that maybe your phone's language is set to a different language, and Jerboa could be using your phone's language preferences instead of your Lemmy preference.
I will play around with the app later and if I find a better explanation I will come back!
(Note: I had a problem posting this comment and had to explicitly set it to English to post)