Well, first of all I have to tell you that not all scripts are easily translatable. You would have to modify the script files themselves and look for the strings used. This is because script developers need to program their own translation system for their script and for a new developer, this might simply be a too hard task to accomplish. It's lots easier for a script developer to simply hard-code a message than implementing it in some translation system.
More advanced scripts, such as Screenshot Sender or Music Now Playing, do have some sort of translation system which lets translators write an INI or XML file with all the messages used in the script. However, the structure of these files are mostly very different between two scripts and therefore translating one script may be easier than another one. This all depends on how the system works and thus you'll need to study the original translation file of the script first and then base your translated file on that original one.
The best thing you can do is study the translation system for the specific script and attempt to translate just that script. If you're in need of some help, you can try to search for a thread about the script on these forums and PM the script developer. Then, for another script, you forget everything about the last script and start all over again.
Off-topic: I recommend you to censor your e-mail address, such as "someone AT hotmail DOT REMOVE-THIS com". Some SPAM bots might read these forums too!
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