Uh, there's those R4SDHC that do have the timebomb in them, the ones whith a year inscribed on the label, like 2020/21,those are really cheap and available, you can use an alternate kernal YSMenu to bypass the timebomb thing. There are also ones without the timebomb, they're expensive than the ones i mentioned above, ask in the flashcart thread for more info on both.
Also again, you don't need either, TwilightMenu++ works fine with the majority of games, saving shouldn't be an issue just describe your problem on the TwilightMenu++
thread for others to help.
Also, do you have TwilightMenu++ installed on the 3DS sd card or a flashcart? And does it fail to save for all games or only one?