The interface need minor revisions.
The following illustrate some of the problems which are part bugs, part incomplete docs.

Replication instructions:

1. Create a new calculated question on a Quiz
2. Configure the question as follows:
Question text: Which the area of a rectangle with base {bs8} cm and height {altr8} cm ?
Correct answer formula: {bs8}*{altr8}
Grade: 100%
3. Click the button Save changes
4. Select "Will use a new shared dataset" on for both Wild cards
5. Select Synchronize on the Synchronization options and click "Next page"
6. Configure the Range of Values for wild cards {bs8} and {altr8} to from 3 to 20 and for from 4 to 25
7. Click on the "Update the datasets parameters" button, just to be sure everything is ok and saved
8. Look at the proposed Item to add and the correct answer calculations:

9. Click on the Add button to add 1 new set of wildcard values:

Result (BUG1): As you can see on the above images, the wild card values and correct answer of the new set added are completely different from the previously shown. According to the help files, this should not occur.

10. Edit the new Item to add to change manually the wildcard values to 4 and 5, for example. The purpose is to input manually one data set.

11. Click on the Add button to add 1 new set of wildcard values

Result (BUG2, probably related to BUG1): The item added is completely different from the one that was defined manually. According to the help files, this should not occur and it prevents the user from defining manually the item to add.

12. Look at the last added set of wild card values and click on the Delete button to delete it

13. Change the Range of Values for {bs8} and {altr8} to 18 to 25 and 22 to 30

14. Click in " Update the datasets parameters", just to be sure everything is ok and saved
15. Select the option "forceregeneration of all wildcards" on the Next 'Item to Add' configuration
16. Click on the Add button to add 1 new set of wildcard values

Result(BUG3): The force regeneration was ignored. The new added set is exactly the same as the one that had been deleted previously. Moreover, it is out of the new range of values defined.