I would like to request the solution as in the topic title.
The auto-completion does not recognise (after reloading) single mispelled words but still does so with regard to phrases containing a correct and a misspelt word.
Another issue is with words/phrases which end in an apostrohe/bracket etc. One can delete them, but after reloading such suggestions return.
I would be grateful for addressing these issues.
Automatic removal of the misspelled words from the Auto-completion list was introduced in 2018 Akua Update 5 (20180409), but from what you say, this feature might need some refining.
For now, please note there is a keyboard shortcut for manually removing auto-complete entries.
Look for " Remove from auto-completion list" in Preferences > Keyboard shortcuts. (Ctrl/Cmd+Shift+R, I think)