gnucash/import-export/csv-imp/assistant-csv-trans-import.cpp:1940-2:
    auto text = std::string("<span size=\"medium\"><b>");
    text += _("The transactions were imported from the file '") + m_file_name + "'.";
    text += "</b></span>";

The break in 3 lines, avoiding markups in translatable strings, is very nice. This technic should be applied on other places, too.

But the center line is almost untranslatable. In de we would use the following ordering of words: _("The transactions were from the file '") + m_file_name + "' imported."
So the expression should become something like 
formatstr(_("The transactions were imported from the file '%s'."), m_file_name)
Then our msgstr could be "Die Buchungen wurden aus der Datei »%s« importiert."