How about adding patch from https://bugs.kde.org/show_bug.cgi?id=154561 to enable hunspell? I applied patch id=22665 to kdelibs-3.5.9-r4 and it seems to be working fine.
If it gets accepted upstream to be included into the KDE 3.5 branch, we'll go with the flow. This feature does not justify potentially upstream bitching about bug reports due to a distribution specific patch. Also I'm interested to keep KDE 3.5 at a low maintenance level. We're few enough.