It is possible to create a custom constraint on a table, so you can add specific checks without having to create a trigger. The message can be created with a dynamic model procedure like this:

insert into #msg
(
    msg_id 
   ,msg_description 
   ,msg_location_id 
   ,severity 
   ,msg_error_code 
   ,msg_regular_expression 
)
select 'err_check_constraint_' + tcc.check_constraint_id                    as msg_id          
     , 'Translation for check constraint error: ' + tcc.check_constraint_id as msg_description          
     , 'popup' as msg_location_id          
     , 0 as severity                 --error          
     , 547 as msg_error_code         --error code when check constraint fails          
     , '.*"' + tcc.check_constraint_id + '".*' as msg_regular_expression --regex that will find the specific constraint 
from tab_check_constraint tcc       
where tcc.model_id = @model_id 
  and tcc.branch_id = @branch_id 
  and tcc.generated_by_control_proc_id is null --only manual

Then, you have to search in generated translation objects, or the message, with the name of the constraint in it. It would be very helpful, when you can translate the message as a detail of the constraint, just like you can do this on for example a column. The trick now, that it is not a translation, but a message with a translation. 

The idea is, that this message object is automatically generated, and that it is available on the constraint as a detail, so you can directly translate it. You need this, don't you?