But I think it would be a mistake to generalize what is said here. Because in most of the shops the plants sold are import plants from nurseries where the 99% of plants are grown emersed. When grown emersed most of the very common plants change form and appearance. They will usualy have woody or stiff stems. Rosettes will have smaller, thicker, more colorfull appearances. After adaptation to submersed life what is said above is OK.
Truuue.... stems do tend to toughen up a bit when grown emersed, but they don't develop woody parts. Emersed aquatic plants tend to have a lot of air spaces inside the stems, and use scleranchyma cells for support (like the stringy parts of celery) rather than developing wood or a hardened entire stem. They usually are very easy to bend versus non-aquatics that tend to be harder to bend. There is a big difference between emersed limno aromatica (for example) and non-aquatic species like Hemigraphis exotica. I suppose it isn't 100% accurate in every case, but it is helpful.
Hemigraphis exotica needs a humid environment, you can't grow it in room conditions directly after being underwater, especially in the winter (the air inside houses tends to be very dry).
Next time try transitioning it slower from the tank to the room, and make sure the soil in the pot is very wet initially and slowly water less and less.
Try getting some Alternanthera reineckii 'rosaefolia'. It looks similar (red and green leaves) and is relatively easy and common in the hobby.
