SUMMARY

Spell checking does not work in Kile, while it does work in other KDE apps, e.g. Kate. If I do a spell check from the menu in Kile it tells me "Spell check complete" without complaining about any obviously misspelled words. Also the automatic spell checker does not underline any words. In the console Kile will print the following line over and over again:

kile(15155): No language dictionaries for the language :  "en_GB"

Here is an example of the console output of the automatic spell checker failing to see an obviously misspelled word:

kile(15155)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::spellCheckDone: on-the-fly spell check done, queue length  1
kile(15155)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::performSpellCheck: for the range  [ (72, 0)  ->  (72, 11) ]
kile(15155)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::installedMovingRanges: [ (72, 0)  ->  (72, 11) ]
kile(15155)/Kate (On-The-Fly Spellcheck) KateOnTheFlyChecker::performSpellCheck: next spell checking "oenuthosneu"
kile(15155): No language dictionaries for the language :  "en_GB" 

To repeat: in Kate the spell checker works without problems. So this must be an issue with Kile, not sonnet or similar. One interesting thing is that the "Spellcheck" settings look different in Kile compared to Kate and the KDE system settings: in the latter two I can choose between four languages (the installed ones: "British English (United Kingdom)", "American English (United States)", "Deutsch (Deutschland)", and "svenska (Sverige)"), while in the Kile editor settings I can only choose one language ("English (United Kingdom)", which seems to be a non-existent dictionary).


STEPS TO REPRODUCE
Permanent error

OBSERVED RESULT
No spell checking possible in Kile, while it does work in e.g. Kate

EXPECTED RESULT
Misspelled words should be detected in Kile

SOFTWARE VERSIONS
Operating System: openSUSE Tumbleweed 20181029
KDE Plasma Version: 5.14.2
Qt Version: 5.11.2
KDE Frameworks Version: 5.51.0
Kernel Version: 4.18.15-1-default
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-6200U CPU @ 2.30GHz
Memory: 7.7 GiB of RAM

ADDITIONAL INFORMATION
I'm using the newest version of openSUSE Tumbleweed. In openSUSE Leap 42.3, which I had installed until recently, spell checking worked perfectly in Kile.