Current 4.3 kttsd has hard dependencies on epos, festival, flite, freetts, AND mbrola. In addition to these dependencies appearing to be optional, epos is ~arch only and mbrola is non-free.
Also, mbrola does not support x86_64 proper, only hybrid 32/64 multilib systems.
The dependencies have now been replaced with an elog notice in pkg_postinst, as per usual KDE practice concerning optional, runtime-only dependencies.