I am reluctant to intervene with two titans of birdforum slugging it out. But what about the hind claw? Is it not supposed to be long in an african pipit (it was even deemed cospecific with richards pipit by some once) It was one of the main characteristics I was told to look out for when searching for african pipit in south west Saudi Arabia where it is a rare highland bird. I don't have experience of the bird in Africa but the hind claw of this bird doesn't look right to me.
I think any opinion to improve knowledge and understanding is welcome from anyone. Note also that Thibaut is usually much better in identification than I'm, especially for LBJ's.
Regarding African Pipit, I've seen them often even higher than that in Western Uganda, including Rwenzori Mountains, that is confirmed in HBW Alive.
Grassland, including fallow fields and other agricultural land, edges of pans, also recently burnt areas; also open areas in towns and villages. Breeds from sea-level to over 3400 m.
For Plain-backed, the fact I've never seen them that high doesn't prove anything, except that is cannot be a common bird (I lived in Western Uganda 3 years), but this is interesting from HBW Alive.
Savanna with scattered trees and bushes in better-wooded areas, open grassland with scattered bushes. Occurs in various open habitats, from short or burnt grassland to fallow land and arable fields. Where sympatric with A. vaalensis, as in Botswana and Zimbabwe, favours floodplains and other wet grasslands. Generally low to medium elevations, but to 2200 m in E Africa.
I think mentioned records at 2200 are from Kilimanjaro and Mt Kenya, and Ruhija is about at 2300 m asl if I remember well.
I don't say it is impossible, that would be a very interesting record.
Regarding the hind claw, I didn't think to look, but I'm not sure it cannot say much. HBW states that local
A. l. zenkeri of Plain-backed has a shorter hind claw than other sub-species, but despite I've several photos of that sub-species, I didn't find a good side view of the feet.
It is possible that hind claw length varies in African Pipit also, but hind claw on OP bird seems to match African Pipits depicted
here.
and HBW quotes for African Pipit
hind claw longer than hind toe
which seems to match OP bird too.
I hope it helps.