Isn't E27 bulb available almost everywhere? The only issue with such downlight, IMO, is due to the poor light throw (dark).

Those recessed downlight, on the other hand, are brighter but chap ayam type don't last long. To replace them without damaging plaster ceiling takes some practice but very possible.

I normally pull out a bit, look for one of the clips and push the housing towards the other clip.This gives me space to insert a finger into the other clip to force it up and release one side. Once a side is released, you can slide it out without damaging the plaster ceiling.

First time memang a bit tricky, I accidentally took out a small chunk of plaster doing so. It gets easier the next time.

I'd say the most "difficult" part is connecting the electrical cables especially if the ladder is not tall enough.

The replacement light, must we use back the same brand in order to fit the bracket?

I see. The reason I asked about 3rd party replacement isn't just about saving money. Proprietary replacement is usually more difficult to source and product lifespan (EOL) may be shorter.