If you want to contribute translations, see howto:translate. Translations on Danbooru should be in the form of annotations that appear directly over the original text. Translations outside the context of the image are hard to comprehend when there are multiple speech bubbles, so translations in the comments should be avoided whenever possible.
Also, bumping years-old posts to the top of the comments page tends to attract downvotes from annoyed users, which can lead to your comments being hidden from view. Consider checking the "No bump" box before submitting comments on old images.
