Question about a Russian localization decision

I was curious about the Russian localization of the game and checked it out, and while both 'Tides still seem rife with mistranslations, that wasn’t what caught my eye.
Markus is translated to “Марк” (Mark), and while some of my friends were upset with that, it actually follows an established grammatical rule. What I’m more confused by is, why did Kerillian become “Кериллан” (Kerillan, missing the second “i”)? As a translator myself, I want to learn what led to this transformation.