What sort of wood found in Southeast Asia is lightweight and can be used to build teething toys for children?
Based on the woods listed in the Comments:
Rosewood would be a great choice in terms of durability. Potential for toxicity is a concern but anyway "rosewood" doesn't mean much these days. Much wood sold as rosewood is either of a lesser species of dalbergia or something that looks (a little) like rosewood but is actually a completely unrelated species. So I think you have to discount this because what you'd buy is an unknown quantity.
Teak may be a poor choice in part because it has a high natural silica content that may wear baby teeth down excessively. Also unfortunately when you buy "teak" these days that isn't always what you're getting and one of the common substitutions in particular is splintery and might be extremely hazardous to use for a teething toy.
Mahogany..... I hate to say it again but "mahogany" has the same issues as the above! The most likely mahogany being sold there is probably not quite as robust as you'd like for this purpose, being soft enough to easily mark with a fingernail. It is fairly smooth-textured and easily worked however.
Albasia is a lightweight wood and light woods are generally quite soft and weak (balsa being the supreme example of this) so I think that rules that out.
So of the woods you list only jabon is left and I think it may be the best choice anyway. Jabon, also referred to as kadam (Anthocephalus chinensis or Anthocephalus cadamba) is a tree that has edible fruits, which is often a sign the wood from the same tree won't give toxicity problems. It is not overly hard so easily worked, but note that it has a wide range of listed densities, so try to pick pieces that seem heavy in the hand as the wood in those boards will be denser and more durable than lighter boards of the same species.
I also like that jabon is a tree that is heavily planted, so not restricted by CITES or on an endangered list like some of the others.