Cajanus elongatus (Benth.) Maesen (syn: Atylosia elongata Benth.; Cantharospermum elongatum (Benth.) Raizada);
Bhutan; India; Myanmar; Nepal; Vietnam as per Catalogue of Life;

Stems sparsely pubescent with long fine hairs. leaves digitately trifoliate, leaflets ovate or broadly elliptic 2.5-4 x 2-3.5cm, acute, base rounded, sparsely pubescent with long fine hairs and glands especially beneath, stipules absent, stipules 4 x 2mm. Flowers 1-4, peduncles slender 3-4cm, bracts elliptic 4mm, 3-toothed at apex. Calyx tube 2-4mm, teeth narrowly triangular 5-8mm. Petals 10-12mm. Pods 1.7-2.5 x 0.5-0.8cm, 3-4- seeded.

Fl. August
On dry ground
Trongsa (Nimshong), Trashigang (Damoitisi). 2000m.
(Attributions- A.C.J Grierson & D.G Long. Flora of Bhutan. Published by RBGE. 1987 from Bhutan Biodiversity Portal)

Rhynchosia himalensis Baker : 15 posts by 4 authors. Attachments (4)- around 1400 kb each.

Location: Champadevi, Kathmandu, Nepal
Altitude: 1878m.
Date: 02 September 2019
Habit : Wild

Attachments (3) – 658 kb, 2 mb & 3 mb.

Attachments (2)- 2 mb each.

Attachments (1)- 2 mb.

Stunning series of images.
It does not match with entry in FOI.
Moreover, Rhynchosia is known for its two seeded pods, which it is not.
Reminds me of Cajanus scarabaeoides, not a 100 % match though. 

Elevation, leaf patter and legume does not match !

Thanks, …, for leading the right direction.
Keys in Flora of Bhutan lead me to Cajanus elongates.
Pl. check at GBIF
To me  appears close.

It’s syn. is mentioned in Check list of Nepal as Atylosia elongata Benth.

Thank you …!
I guess … has given the correct ID because elevation for Cajanus scarabaeoides
does not match.
Enclosing one link for further analysis.
Thai Forrest Bulletin

Attachments (1)-pdf- 118681-Article Text-358704-3-10-20180723.pdf

how recent is the elevation related data?

Could you please check the link …!
And then recent book I have mentioned earlier also says so !

In the pdf you sent. its from 2018 ad its listed that Cajanus scarabaeoides is found in 10 m to 1500 m asl (in their ecology section of each species: lowest I found was 800m asl for c. goensis, and rest were found all the way up to upto 1800m asl.)

Please have a look at the link : Research gate: Cajanus elongatus (Benth.) Maesen (Fabaceae): An addition to the legume flora of Odisha, India

What aspect do you have doubts about?
If it is calyx, calyx here is mentioned as
“Calyx cup-shaped; tube 3-5 mm long; lobes linear-lanceolate or narrowly triangular, unequal, 5-9 x 1-2 mm; two upper calyx lobes connate for up to half of their length; outside moderately to densely hairy and with sessile glands; inside glabrous.”
Some friends suggested it to be Cajanus crassus (Prain ex King) Maesen but the elevation does not match.