I don't know what you mean with "In version v3.10 of the add-on EN 15804, I could change the order of the impact categories of an Impact assessment method or even delete some" because the versions of the database have nothing to do with the fact that you can re-arrange or delete impact methods.
In version 3.11 we slightly changed the default names of the impact categories, so that they are more clear distinguished between mandatory core indicators and optional/additional ones. We have not changed the actual official indicator names, only the information in front like "Core (EF3.1) | Global Warming Potential - biogenic (GWP-biogenic)".
But you can any time create you own order of impact categories or you can any time give your own names of impact categories, depending on the program operator. Just copy/paste all impact categories that you need and add them to an empty new method. You can then rename the impact categories or put them in the order that you wish, by putting a number in front, like "1 - Climate change" and "2 - Acidification" as an example.
In an upcoming update of the EN15804 add-on we will also add some very common ordering of categories from top to the bottom as it is needed in EPD International and IBU as two of the largest programme operators. Apart from this, users are always free in creating there own sorting, which facilitates copying the results outside into a template / a document sheet for the EPD.
