.rpa files are Ren'py archives. You can easily extract them using programs like RPAExtractor to get the individual script files. But those script files are in then in the .rpyc file format (which is a compiled script file extention used by Ren'py games). Those aren't for editing purposes. You need the .rpy versions of the script. It's a bit complicated, but it bascially works like this: As a developer your work with the .rpy scripts (which you can easily edit in programs like Editra). The Ren'py game than translates those .rpy files to .rpyc that it can use to actually run the games.
To make translation a bit easier for you, here are the .rpy script files of Blooming Love so you don't have to go through the annoying process of extracting them from the game:
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You can make the translation changes to these scripts. If you drop the translated scripts into the 'game' folder of the Blooming Love game folder, the game should automatically use the translated scripts