GT4T’s ‘fix MT with glossary’ is not simple search and replace.
If a word is CONSTANTLY translated wrong, simple replacing of the MT translation with your own translation will work.
But with GT4T it doesn’t matter what MT will translate a word into as it actually replaces the source word.
GT4T glossary file contains ‘source – target’ pairs, not ‘wrong translation – correct translation’ pairs.
The post-translation of GT4T works like this.
1) Mark a word as untranslatable so the word will remain untranslated in the translation.
2) Replace that untranslated word in MT translation with your glossary.
This feature thus can be used to mark ‘untranslatable’ terms. If you add a term to GT4T glossary leaving the translation the same with source, that term will always remain untranslated in MT translations.