The markTransFound method removes the trans[Not]Found info from segment data received from term tagger, because trans[Not]Found state is recalculated internally.
The regular expression to remove this existing state is to unspecific, currently:

> $seg->source = preg_replace('" ?transN?o?t?Found ?"', ' ', $seg->source);
> $seg->target = preg_replace('" ?transN?o?t?Found ?"', ' ', $seg->target);

This should be changed so that the regex matches only in term markup. This prevents that the string transFound is removed from normal segment text.

This should / could be done with TRANSLATE-296.