Quite often, games originally designed for the Japanese language offer no support for text wrapping.
In other words, when the text reaches the end of the line, there is no internal system to have it continue on the next. Instead, it's down to the translators to force it by adding a manual line break.
Sometimes, it's worth spending extra time to craft the translation around those limits, carefully picking the right words in order to make the best of the very limited space.
But in most cases, we found it more productive to simply keep the translation around 10% shorter than the available space (characters per line * number of lines) and then use a macro to add line breaks automatically.
You can download it here: CutText.zip
It's all rather self explanatory: copy the text you want to format, paste it on column A, then set the length as needed - either modifying the formula inside columns B or typing the length directly inside columns E and F.
If your text already contains line breaks, for example a paragraph, they will be preserved. If the text is too long for the limits you set, the macro will throw an error and you will need to increase them or shorten/tweak the text.
Needless to say, with a bit of Excel experience you can easily use the formula directly inside your own files, but that should be a good starting base for everyone.
Good work (and don't forget to do a final proof before delivering!)