I'd posit that we're actually seeing 2 (or even 3) blade styles here:
1a. Basically a fairly typical Moro kris: a pretty much straight, double-edged blade with only slightly asymmetrical edges and tip (since non-archaic Moro kris are rarely utilized for stabbing, this doesn't really change the ergonomics that much. Albert's piece and the one from the Tropenmuseum
in this thread are good examples.
1b. This variant conforms to the definition given above for 1a. However, the blade tends to be shorter with a pronounced belly: Pretty much a cross-breed between a Moro kris and a barung. Here is an old example
from Holstein.
2. A long, curved sabre blade (often a repurposed import blade to which a Moro base with gangya got attached by forging); usually single-edged (or with a limited false edge).
Here is an example.
Type #2 often looks a bit crudely worked and they seem to appear during the late 19th century while the other variants appear to be older, genuine Moro styles.
Regards,
Kai