Yes, M'sia roof construction generally do not have soffit vents. But then the roofs are also not air tight, so there is a lot of air bleed to replace the air removed by the ventilator. There is actually fibre cement board with slots cut in specifically for soffit installation in M'sia. (Eg : UAC Duravent)

I would agree to using an insulation in the attic, but I would go for rock wool instead of blown-in. Reasons being it being a continuous mat instead of loose fill, does not need a specialist installer, easier to manage in the future if other local tradespeople have to deal with it.

I wouldn't focus on the cost at all because this is a "do once, last forever" deal.