two-column comparison documents to translate

I agree, Excel is faster to process large translation tables. However, the biggest downside of Excel is the fact that it does not support AutoCAD line breaks (because Excel line break is reserved for AutoCAD paragraph breaks) and AutoCAD tab characters (since there is no way to enter a tab character inside Excel files). Usually, AutoCAD translation tables are not large so Word is perfectly OK for them. I understand the way you use Excel files to store all past translations and of course you won't be able to use Word files for your workflow because of Word's file size / speed limitations. So, if you want to avoid all the limitations of Excel translation tables which I mentioned above, you need to use Word translation tables + translation memory software (CAT tools). This way, you won't need to run all the comparisons, the CAT tool will simply store all your past translations in the translation memory and you will be able to pretranslate generated translation tables from this translation memory.