Grammatical mistake intentional? The Bear and the Young'uns' Cares

[Rutelor]

Although the problematic usage in it has become quite pervasive, the following excerpt from The Bear and the Young'uns' Cares (Main Storyline, lv. 27) is grammatically incorrect:

Gundobald: "Two decades ago, this anger drove my brothers and I to rise against the despot..."

What I don't know is whether the original text in Japanese has Gundobald (a figure of considerable stature and authority) actually making mistakes, as part of the character's delineation. I would venture to say no.

[Corvinoobus]

As you rightly surmised, this mistake was not intentional. The issue will be addressed with a future update.