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As a reasonably experienced FIC instructor and as a CFI/HT my personal experience is “I haven’t found one yet.”
I interview for FIs frequently and find those from Poland/Eastern Europe are poorly prepared in terms of rules, regulations, lesson structure, content, briefing/debriefing technique and consistency of terminology. Little concept of demonstration, teach and practice or of breaking the elements down into more manageable pieces. It’s like the 125hours ground hasn’t been correctly delivered if at all.
However, I take each case individually when a CV lands on my desk and find there are some good candidates but predominantly ‘average’ seems to be the norm.