What and how to write about these problems in my CV when I apply to phd program in Europe
I am handling PhD admissions for CS at a British university. None[1] of the information you mention in your post seems relevant for a PhD application to me. There is no need to say anything at all about how exactly you spend your January.
Similarly, preferences for interview dates should given in a far more generic way. For example, &quot;I am unavailable on May 9th.&quot; or &quot;I would prefer a later date over an earlier, if possible.&quot;
[1] Except that you got a MSc in Mathematics in June 2020, that is important of course.