Blender stack exchange receives allot of "import export problems" questions. Sometimes it is nearly impossible to figure out which software package is responsible. If blender is causing the issue, then it naturally follows that the question is topical, but if that is not the case then it isn't. If no one knows whether it is blender, then know one knows whether it is topical. Should it be closed...?
In either of your cases it should be closed.
If it is too unclear to figure out where the problem lays, close it as unclear.
If the problem is clearly out side of blender, close it as off topic.
The obj exported from blender does not display right in my custom built game engine.
Closed as off topic because it is not a problem with blender.
Import export trouble between three.js and blender.
Most likely closed as unclear what you are trying to ask.