Teya Customer Relations Agent interview questions

My recent job interview did not result in a job offer despite having achieved three of the four stages of the interview process and having all the needed skills for this position. This included a Czech language interview with an HR representative, an English language interview, and a trial day of two hours in Czech. After this, the offer was withdrawn seemingly only due to my language proficiency. I am confident that my language skills were excellent for the position I applied for. During the trial day, I was given a task by someone from the team, where the task was written on spot and had no clear instructions. She simply told me to "write it your way, with the most important factor being how I would treat our customers". All email communication was conducted in English, and the manager of the Customer Relations team did not speak Czech at all. This likely led to me being judged harshly on my Czech grammar. Huge disappointment.