> The prefix de- is used in Czech normally since forever and to this day
It's only used in loan words. Like "depilace" is a normally used loanword in Czech, non-loan word variant would be "odchlupeni". But "dechlupeni" (using "de-" instead of "od-" + native Czech word) would be completely nonsensical.
Claiming that "defenestrace" is originally a Czech word seems absurd to me. It might have been "invented" in Czech lands, but clearly from the latin form.
It's only used in loan words. Like "depilace" is a normally used loanword in Czech, non-loan word variant would be "odchlupeni". But "dechlupeni" (using "de-" instead of "od-" + native Czech word) would be completely nonsensical.
Claiming that "defenestrace" is originally a Czech word seems absurd to me. It might have been "invented" in Czech lands, but clearly from the latin form.