Translation:That book costs one hundred and ninety-five euros.
I understand that it is harder to type Arabic numbers using a Czech keyboard than with other layouts, and all the hardships in creating a course. Hence, it is fine to provide initial set of answers with words only.
As to the current automatic substitution algorithm, I understand that it is not perfect. There are other confusions involving numbers, such as confusing the pronoun 'one' [as in 'one should respect the endeavours of our volunteers'] and the numeric 1. Therefore, we users might as well accept such imperfect 'artefacts'.
However, a workaround seems also possible, if it is not too tedious for your team: learners submit reports with the answers using Arabic numbers, and your team just approves them. In some other courses, writing numbers up to 1 600 000 000 in Arabic numbers also gets supported. I guess that it is not made by inputting so many individual numbers in those courses, but by using the report system: in this way, not all numbers have to be supported, but only the numbers involved; if the report manager allows to directly approve a sentence, you might save the effort to type the numbers.
Usually we can always type numbers in English translations, including in the Czech course. Here the problem is that there's a clear mistake in the numerical answer. I think that if the paid staff doesn't have the time to correct their own mistakes, they should give volunteers the means to do so.