Eriolaena spectabilis (DC.) Planch. ex Mast., Fl. Brit. India 1: 371 1874. (syn: Eriolaena ceratocarpa Hu; Eriolaena malvacea (H.Lév.) Hand.-Mazz.; Eriolaena szemaoensis Hu; Jackia spectabilis (DC.) Spreng.; Microchlaena spectabilis (DC.) Endl. ex Walp.; Sterculia malvacea H.Lév.; Wallichia spectabilis DC.);
Himalaya to China (C. & SE. Yunnan, S. Guizhou, NW. Guangxi): China South-Central, China Southeast, East Himalaya, Myanmar, Nepal, West Himalaya as per POWO;

MS, Nov., 2021/64 Tree/Shrub for id: 2 images.
Location : Riau road
Date : 29-07-2015
Habit : Tree or Shrub
Habitat : Wild

Eriolaena sp.,

Any keys?

Not listed in Flora of Mizoram. I think it is Eriolaena spectabilis

Yes, you seem to be right as per POWO specimens- one
I checked distribution of all the species in BSI Flora of India.
There is another species Eriolaena wallichii, which is shown distributed in eastern Himalayas as per POWO, but looks different.




References: POWO specimen- one  Catalogue of Life  The Plant List Ver.1.1  WCSP  IPNI  GBIF (High resolution specimens) BSI Flora of India  Flora of China  FOC illustration  Annotated checklist of Flowering plants of Nepal  Pan India Bouquets  India Biodiversity Portal  Useful Tropical Plants  The Eriolaena Page – Malvaceae Info