I have discovered together with samelian error in tdelibs PKGBUILD.
Error everyone (including me) was was getting (including) me while
bulding on clean arch installation was coming from trinity bin dir
missing from PATH. There is need to use tqt-replace which is part of
tqtinterface and can be found in $trinity_prefix/bin during tdelibs
compilation. tqt-replace translates tqtinterface ui files to original
qt ui files because uic cannot generate correct tqt ui files. Yet, it
seems that after tqtinterface is installed form PKGBUILD its bin
directory isn't added to path. This causes impossibility to access
tqt-replace script and and translation of ui files. I resolved this
issue by exporting path in tdelibs PKGBUILD, but I think that the
tqtinterface package should do this. I've seen that qt3 package
installs /etc/profile.d/qt3.sh which exports qt3 bins into PATH, same
should be done by tqtinterface package I think.

P.S: I'm sorry if my mail/english was a little incomprehensible, but
it's 1:18 where I live and I can't really think straight.

Attachment tdelibs.patch