For the fiscal year 2008, the US State Department issued two IR-3 visas, 0 IH-3 visas, 0 IR-3 visas, and 0 IH-4 visas for Sri Lanka. The statistics mean that two children came to the USA from Sri Lanka for purposes of adoption. Check out this website for current information:
Welcome to Adoption.State.Gov.
In order to adopt a child into the USA, an agency accredited by the USA government must agree to represent the prospective parents in the adoption of the child from another country. Even if the prospective parents are Sri Lankan, one must be a US citizen in order to immigrate a child into the USA.
With regards to Sri Lanka, if the Sri Lankan has relinquished their Sri Lankan citizenship, there appears to be no preference, unlike India, for adoption of Sri Lankans outside the country of Sri Lanka. Having checked with a Sri Lankan adoption attorney with the assistance of a couple who have adopted twice within Sri Lanka, we were told that we had to go through the foreigner regulations for adoption and could not use the same rules/procedures/process as those who are Sri Lankan living in Sri Lanka. More recently, we were told by another Sri Lankan family that after looking into adoption in Sri Lanka that they have strict age requirements thus barring anyone 40+ in age from adopting a child outside the country, thus making it difficult for most prospective families.
On an extremely rare occasion, there might be a Sri Lankan child available within the Diaspora or within a refugee camp in another country; however, most of these countries (with the exception of India) do not allow their children to be adopted to countries outside of their birth countries so prospective parents need to reside in those countries and be connected to the community and let it be known to birth parents that they are looking to adopt. India has had a few rare exceptions of adopting out children as Indian citizens who are born in refugee camps; however, Indian citizens then OCI card holders then foreigners (which include Sri Lankans in the mix) can adopt. It's not an easy task to adopt a Sri Lankan child from India as one would have no way of knowing until a referral was given to prospective parents.
One cannot work with an agency that is located outside of the country where they are residing. There is at least one exception given to US military/gov't employees working abroad who can adopt US citizens and who can work with stateside agencies.
If one were looking to adopt a child of a particular language/ethnicity or who was born in a certain location, it is not easy to do so. India, for example, does not have a system whereby parents can be matched with children who share cultural, linguistic, and ethnic backgrounds and even Indians may find that they are not able to adopt a child who is of the same ethnicity and language as their family. In Sri Lanka, one adoptive family said that their child was half-Indian, half-Sri Lankan and that a relative had adopted a child that was half-Sri Lankan, half-Middle Eastern.
The other challenge is that Sri Lankan children in the USA are only available via birth mothers or foster care systems. Note that each county has their own foster care system so there will be thousands of foster care systems to contact. There is no central national clearinghouse of foster care children; however, very difficult to place children with severe disabilities and/or who are older might be on such webpages or lists. The challenge is that there are very few Asians in the USA available for adoption and then Sri Lankans are lumped into the Asian category along with all of the ethnic groups of Southwest, South, North, East, and Southeast Asia! Never heard of a birth mother of Sri Lankan ancestry in the USA looking for adoption as a possibility, but there have been a rare few from the Indian community in the past several years who generally post directly to Indian adoption forums looking for a South Asian family to adopt their child.
Good luck as you pursue adoption! I would imagine that not only does Canada have adoption agencies with Sri Lankan adoption programs that they would have children available in their foster care system who would be available for adoption. I wouldn't be surprised if there were birth mothers looking for adoptive families in the Toronto area since there's a very large population of Sri Lankan-Canadians living in that area.
Best wishes!