For plasma5 and frameworks5 based apps, as I said, the freedesktop.org
speced locations are normally used. That's $XDG_CONFIG_HOME for
config, and $XDG_DATA_HOME for app data. If those aren't set... well,
let me point you to the freedesktop.org website for the specs and you
can read it yourself, but try ~/.config and ~/.local/share .
https://www.freedesktop.org/wiki/Specifications/
FYI: here's a little POSIX shell snippet i use for diagnostics that can
show you current XDG settings:
echo "[XDG Environment]"
while read var default; do
printf "%24s = %s\n" "${var}" "$(eval echo \${$var-${default}\(\*\)})"
done<<"EOF"
XDG_DATA_HOME ${HOME}/.local/share
XDG_CONFIG_HOME ${HOME}/.config
XDG_DATA_DIRS /usr/local/share/:/usr/share/
XDG_CONFIG_DIRS /etc/xdg
XDG_CACHE_HOME ${HOME}/.cache
XDG_RUNTIME_DIR /run/user/$(id -u)
XDG_SESSION_ID
XDG_SESSION_COOKIE
XDG_SESSION_TYPE
XDG_SESSION_CLASS
XDG_SESSION_DESKTOP
XDG_CURRENT_DESKTOP
XDG_SEAT
XDG_VTNR
XDG_DESKTOP_DIR $HOME/Desktop
XDG_DOCUMENTS_DIR $HOME/Documents
XDG_DOWNLOAD_DIR $HOME/Downloads
XDG_MUSIC_DIR $HOME/Music
XDG_PICTURES_DIR $HOME/Pictures
XDG_PUBLICSHARE_DIR $HOME/Public
XDG_TEMPLATES_DIR $HOME/Templates
XDG_VIDEOS_DIR $HOME/Videos
EOF
echo "(*) indicates variable unset and a default value substituted"
