I know how to do subs with Aegisub. If I just had the script in English I could turn it into a subtitle file. Although using already existing Chinese softsubs, there is no need for timing anymore and we just had to translate the Chinese text into English using any text editor. E.g. a softsub looks like this in an editor and one could just directly translate the text without touching the timing/formatting. With Aegisub you have a lot more options and a better overview, although again there is only the need to translate the text as the timing, typesetting, etc is already done.