It's not #EndRegion, it's #End Region. The space is what's throwing it off. Either way, it just seems broken if you were to start typing (without using any shortcuts) the letters #,E,n,d,<SPACE>,R,e,g,i,o,n it will give you "#End If Region". As soon as you press the space bar, it auto-completes to "#End If.
I tried #e and TAB and it auto-completes to #End If.
I'm using B4A v3.80, Win7 Professional SP1, 64-bit if this helps.