Issue re-solved. Here's what was happening:
Objects in the loaded scene (collada.scene.children[0]) seem to be scaled by factor of 0.025. i.e. scaled down. This isn't a problem because objects become visible after setting correct zoom, camera distance, etc...
At this point, Sketchup objects (those which are not Sketchup Components) are visible but Sketchup Components are not visible.
The reason was that sketchup components and groups are further scaled by the same factor 0.025. i.e. components are scaled by factor 0.025 compared to objects which are not components.
This means components were rendered much smaller in size compared to non-components.
The solution is simple.
After the collada is loaded, iterate through all components as well as non-components and set their scales to 1. There's still one more thing to be done. At this point the components are visible but they don't appear in their correct positions. This is solved by multiplying the positions in the same proportion by which they were scaled up. i.e. multiply the positions of all objects within the component by (1/0.025)