I would try to get as close as you can to what should be in there but not lose any sleep over it. Any of the oils you're likely to find will physically mix with each other so its not going to be like mixing oil and water. I'd be amazed if you - or the bike - could tell the difference between 5W-40 and 10W-40 other than by what's on the label. I certainly wouldn't change it until the normal interval had passed.
The bit at the end of the spec, where it says JASO MA2, that's about whether it will cause your clutch to slip. MA2 marked oil is supposed to make sure that doesn't happen. Again, like everything on the internet, some people say it's important, other say it isn't.
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