The main idea is downloading the words in a schedule in order to use it offline.
I have previously read that the reason renshuu currently doesn't offer offline usage is because there would be too many things to download. This is by all means true; there are audio files, images, usage notes, etc.
My suggestion is that you would download just the text translations, not the images and other things.
Based on my calculations, 8000 terms of 200 characters with 4 bytes per character uses 6.4 MB, which isn't significantly large, escpecially when considering the scale. This is only true if all the terms are in one file though.
This suggestion/request is probably a big ask, but it would be really useful for long distance travel.
That is not how renshuu works, unfortunately. You are making the assumption that the entirety (or even part) of renshuu's business logic, templating, localization files, etc. are present on the device. This is not the case - the entire page is generated on the server, then sent over.
There is no way getting around this without duplicating huge chunks of code on the mobile deployments of the app, while simultaneously maintaining separate copies for those who access the website. As a solo developer who does not want to abandon the model of "keep renshuu free and ad free", going off in this direction is not realistic.
