if professional translations are too expensive you might want to consider making a crowding project out of it. Microsoft did that with the Minecraft launcher, for example. Then anyone who has a free crowdin account can translate parts of the game and the translations can then be approved or improved by others.
Hey! Yes, it could be an option, but it relies very heavily on having enough people to translate so many words, and despite being able to approve others work, it also really needs to be edited and proofread by a professional to be release ready. Plus, we aren't very comfortable with unpaid work. Thank you for the suggestion, though!
Obviously it's ultimately your decision, and one does see crowdsourced translations in FOSS software more
The fact Python and especially Ren'Py are free to use, open source, and allow their commercial use without even so much as a royalty, with theor developers being faceless and unappreciated by most, makes their use an extreme form of unpaid work, versus people who enjoy(ed) your work and wish to make it available to a wider audience... It's a rather odd reason to give.