About 30% of the spelling errors have not been fixed. Some of them will be fixed in the next run. Ultimately all errors will be fixed but it is so annoying to have to do it several times 
The situation is much worse in Calc, none of the changes thus applied ever get applied.
If you need to do that frequently you should reconsider your writing habits. This won’t be required, if using paragraph styles having set Polish as their language and others having English (see Styles -> Edit Style... -> Tab: Font -> Option Dropdown: Language ). To define new paragraph styles use Styles -> Manage Styles. BTW.: Even character styles could have their own language setting.
Just switch the input language according to the actual language required (but, yes, defining styles is a very good idea). That is enough in most cases (however, there is a bug report for Linux).
These are not my writing habits. I have to handle documents created by somebody who is technically hardly literate. There is little hope they will ever understand the problems they are causing. They are TOO IMPORTANT to be bothered. That is why I need good software support.