The automation editor allows selection of multiple patterns, but not joint editing. It will only edit in the selected pattern (you can guide yourself in the matrix). This is an intrinsic limitation of how Renoise is programmed by pattern separation. But even so, I think this could be improved a lot still. Unfortunately, Taktik has not spent his time focusing on the automation editor to dramatically improve it. Apparently he is satisfied with what there is, otherwise he would have improved it. It is also true that it is a lot of work.
For example in the automation area, you can select pattern 1 and 2, but if you are located in pattern 2, you will only edit or delete there (AFAIK).
By the way, you can select the whole pattern by clicking on the top bar (above of the envelope).