"Ninapenda kujenga nyumba nzuri"

Translation: I like to build a nice house

[JO_NA_KA]

i must be capitalized?

[brjaga]

Report it. Hopefully the incubator recognizes a change in case as a change, since sometimes systems do case-folding before uniqueness checks

[TwoEyedWink]

Is there anything wrong with "I like building nice houses."?

[CeeCy47]

No, you are correct