As an American, I use:
- few - 3-5
- several - 5-7
- some - less than many (depends on what's being counted)
- many - more than all of the above
I'm not an authority or anything, but that's roughly what the usage seems to be. I don't know what the Esperanto equivalents would be. It seems terms for multiples are somewhat cultural.
If I may assay this issue. Again experienced, but not professional level. The list above is a good place to work from:
A couple = unu-du (usually 2 of something)
Few = Malmultaj, kelkaj
Several = pluraj
Some = (referencing an amount of unspecified items) iom (kaj kelkaj aliaj vortoj)
Many = multaj
The same concepts in other languages might also fit these categories but I wouldn't worry if French or Chinese has differing divisions. Just use this as a guide and not the Rosetta Stone.