Hi ,
What I understand is that you have a configurable product in a sales order, the configuration is from a variant and you have configured this product already. Now you want to what table stores the selected values of characteristics. Am I right?
If so, the values of a product in a sales order is stored in ibase. You may use report rcbasetableinfo to get the values if you have the instance number. Or you may try if you can find it in tcode IB53 or IB56.
I do not know which table stores these values. But I know a workaround. Run crm_order_read and you will get the values from ET_CONFIG -> CUVAL.
I am not sure whether I have answered your questions. Nevertheless, I have provided what I know. Hope it could help you a bit.
Spencer