In the "Language editing" on the "Check for untranslated words or phrases" tab you see all untranslated strings. After clicking on the string you see the "Edit words or phrases" page and this page is scrolled to some location inside it (say, #missing20 ancor).
There is mistake in ancor number calculation, because of which the page is scrolled to wrong ancor.
It's because of inconsistent numbering of ancors in these pages.
The first page "Check for untranslated words or phrases" counts all untranslated string in main language file <language>_utf8, despite of whether it has been translated in local translation <language>_utf8_local.
The second page "Edit words or phrases" has ancors only for strings which are untranslated both in the main and in the local language file.
Solution. Either 1) dont make links for lines with "// translated only in _local" in the "Check for untranslated words or phrases" page, or 2) make ancors for strings with only local translation in the "Edit words or phrases" page.