Hi Ondrey,
for me your workflow is working fine. But you have to type fast because there is a timeout
after each keypress. After the timeout the search will be considered new and previously
entered letters are forgotten. I'm not aware of any config option to change this timeout.
Anyway, there is also the advanced search bar feature. In "Settings->Configure
Krusader->Panel, under "Search bar" activate "Start by typing". Now, a search bar will
open in the panel when you press any key. There is no timeout but instead press escape to
close the bar again. Also note the three different search modes.
Cheers
Alex