Also it was using the wrong field for translation comment.
@ -291,7 +291,7 @@
<item row="0" column="1">
<widget class="QTextEdit" name="trackersList">
<property name="toolTip">
<string comment="A tracker tier is a group of trackers, consisting of a main tracker and its mirrors.">You can separate tracker tiers / groups with an empty line.</string>
<string>You can separate tracker tiers / groups with an empty line.</string>
</property>
<property name="acceptRichText">
<bool>false</bool>