For those that are interested and build from source themselves, I am pushing most of this work to my own github site:
https://github.com/kevinhendricks/Sigil
As of right now the following has been implemented (roughly)
1. User can now specify a secondary dictionary for inline red squiggley spellchecking and that should work.
2. Ignore word lists are now cross language and no longer added to any dictionary
3. The SpellCheckEditor dialog, should now happily spellcheck words in multiple languages as determined by the lang and xml:lang attributes on html tags. It does use a simplistic gui where language code is used as a word prefix. That will most likely be changed before any release to use a separate language column. But for now, the simple gui is being used.
4. Updating words from suggestions should now work in the SpellcheckEditor dialog as well.
5. All UserDictionaries have been temporarily disabled until we figure out how to use them in a multi language environment more effectively.
Feel free to check it out and play with it and let me know of any bugs/issues/crashes that happens.
Once we figure out the best way to handle UserDictionaries, I will push everything to Sigil master for testers to play with the Travis and Appveyor CI builds if they so desire.