Shopware only accept snippets files in .json format.
How to handle multiline text with different number of lines for different translations?
If you want to have the different number of lines in each language(For example 10 lines in English and 2 in Spanish), you have to create only one snippet but with different text inside, using line break as @tinect wrote in this thread https://stackoverflow.com/a/75177091/21048350.
The English version will look like this: "text\ntext\n...\ntext" and Spanish: "text\ntext"