Good thing is to del spellchecker engine at all.
It has no Unicode support and some issues. Some words cannot add to dict. Dialogs not mine.Cannot change dialogs.
I start port of Cudatext plug (spell checker).
instead of built in spell check code.
Plug has less options. less dialogs. but it is using Hunspell. it is supportin Unicode. less optikons such as "correct DOuble caps".
If you remove old spellchecker and provide new spell checker as addon only, then new spellchecker should be available in toolbar. It is very inconvenient to click through addon menu tree to use new spellchecker.
I see. As I don't like to have so much functionality provided as plugin, I stick with older SW version which has all necessary functions built-in. Maybe I switch to Cuda later if it is same powerful as SW.
I know that splitting features into addons gives better handling for developers. So it's best choice for CUDA and I understand your effort in doing this.