According to conversation in TEIID-3112 this is a Designer issue. If I understood correctly, it has been fixed in Teiid and now the changes have to be made in TD SF importer.

I have a VDB with Source model that is created via SalesForce importer and I am getting this error:

Didn't understand relationship 'Opportunitys' in FROM part of query call. If you are attempting to use a custom relationship, be sure to append the '__r' after the custom relationship name. Please reference your WSDL or the describe call for the appropriate names

when trying to submit this query:

select distinct YEAR("Opportunity"."CloseDate") as "Opportunity_CloseDate1" from "SalesForceSource".Campaign AS "Campaign" LEFT OUTER JOIN "SalesForceSource".Opportunity AS "Opportunity" ON Campaign."Id" = Opportunity."CampaignId" order by YEAR("Opportunity"."CloseDate") ASC LIMIT 0 , 32

It works without problems with dynamic VDB.