It’s not easy to overwinter tropical hibiscus under average household conditions. The house is just too warm, with humidity and air circulation too low for them to truly thrive. So I don’t think the issue was your watering – it’s just a difficult situation, and even more so because of the braided stems. For best results, keep your hibiscus in the brightest, coolest spot in your home. It should not be exposed to freezing temperatures, but nor should it get any blasts of hot air, which can lead to leaf loss. And of course, put it back outdoors as soon as the weather allows so it can recover. Fertilizer is definitely a good idea to get it back on track once it gets outside.