Hi David,
I've got two takouba on hand at the moment that are probable export blades (with takouba it's often hard to tell precisely what's native/export as some of the native blades are darn good quality but the basic dimensions should be the same anyways).
No calipers at the moment but blade widths are 4.5cm and 4.8cm at the base, significantly larger than Charles' piece at roughly 3.8cm. I would call these two typical takouba in the triple fuller pattern. I would caution that due to different production 'runs' and models of these blades none of this may be particularly conclusive in terms of ruling out origin for Charles' blade, but from Charles' description and the photos it does not appear to me his blade has been extensively modified or re profiled. In conjunction with the smaller size I would have difficulty being convinced that this is a modified trade blade, but rather, if European, a pattern made for this market.
I would note that similar fullering exists on some Indian blades as well and of course piso podang are found with straight blades occasionally that seem to be in the same pattern as takouba/kaskara. How relevant that may be I have no idea.
Cheers,
Iain