Here is a script I wrote exclusively for Planetside Forums Light/Dark themes. It will add the Google Translate API to Planetside as well as add a dropdown selection to the top of the page.
You can install the script with Tampermonkey and the rest is handled (once enabled). Simply extract the JavaScript file and import it with the Tampermonkey plugin, or install it directly from GreasyFork
Chrome: https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo
Firefox: https://addons.mozilla.org/en-US/firefox/addon/tampermonkey/
Download the Script: https://greasyfork.org/en/scripts/389280-co-uk-planetside-was-tools
Or install it manually from the attachments.
Let me know if you experience any problems. The only one i discovered so far is it breaks the upload feature of new posts, so it cannot be ran on that page (so will not be present on posting). Not sure what googles API is doing to interfere with something so specific.