The automatic spell check is underlining words that are spelled correctly. Although I have this problem with the English language, I read on some forum where it happens in other (perhaps all) other languages. According to the "official documentation" (which begs for details and is lacking through the board for all of KDE), as well as unofficial sources that filled in the missing blanks, my system meets all dependencies, and other applications that rely on them do not have this problem. My specific platform "Antergos" is not in the above list, but it is ArchLinux under the hood.
Does this bug still exist? if so, could you post more details, as in examples of words kate marks as misspelled?
No, it seems to have been corrected within the last month or two. In that time I have had several updates (rolling release) and even reinstalled the OS on this (Used but new to me) PC just two weeks ago, and the one I was using when It happened. Sorry for not reporting this, but it has been a long and tumultuous time since I reported it, with plenty of new bugs and one major annoyance, which prevents users of KDE from running root actions in Kate, Dolphin and other apps. And It's also the first time since reporting the problem that I was ever contacted by you on the issue.
Thanks for verifying!