I just tried to change the mapping of chebi:17214 to chebi:1467. I did not succeed and in the process I noticed several oddities.
1. For Rhea:13365 I got the message: The resulting reaction already exists in the database.
This is not true. When I search for 4-methyl-2-oxopentanoic acid I only find Rhea:13365
2. Rhea:24647 was included in the list. This I think is an error as 24647 is a complex reaction consisting of Rhea:13365 and Rhea:11201.
Complex reactions should not be included in such a change mapping scheme since they will automatically change when the underlying simple reactions are changed. Furthermore, it should not be possible to change them directly since they depend on the underlying simple reactions, so updating them may lead to unexpected behaviour (see below).
I tried to perform the update in the development tool, and I could see no difference when I looked at 24647 again. I also tried to repeat the update, and saw both reactions again. But now 24647 (also) gives the message: The resulting reaction already exists in the database.