I believe your light isn’t sufficiently strong enough for the hibiscuses. I have 5 that I brought indoors and I keep them in a grow tent and use quantum board grow lights (like a setup for growing marijuana, but I only have tropical plants 😂) and they thrive in there. I would recommend getting something like that type of light and probably adding a humidifier and seeing if that helps.
2022 Update Diode SPIDER FARMER SF1000D LED Grow Light Use with Samsung LM301B Sunlike Full Spectrum Grow Lights for Indoor Plants Seeding Veg Flower Growing Lamps 3000K 5000K 660nm 760nm IR https://www.amazon.com/dp/B084L1Y7KR/ref=cm_sw_r_cp_api_glt_fabc_CJ2SY8N8R3TZWR4RX4XZ?_encoding=UTF8&psc=1
This is the light I have, I bought it in a lightning deal for $70 and it worked so well that I bought another one. However I have a bunch of plants in my tent so I don’t think you need more than 1 of these
I'm sorry I forgot to add the link for the stake things I use
HESTYA Watering Stakes Automatic Watering System, 10 Pack Plant Self Drip Irrigation Slow Release for Indoor or Outdoor Houseplants https://www.amazon.com/dp/B07C4NMHPP/ref=cm_sw_r_awdo_navT_g_63ZNHCTRDPQSGXZB7QW7