I honestly didn't know it was more correct to put it there.
I did look into documents and utilities at romhacking.net.
The thing is I found an editor that seems better and more put to date but not mentioned on the romhacking.net downloads: https://github.com/cfrantz/z2edit
And documentation regarding the rombanks also missing in romhacking.net.
This give me the impression that either I'm looking at it wrong or the Zelda II community is gathering somewhere else.
Thanks for the link to data crystal, the information there only mentions older documents, editors and hacks, seems to not to have been updated on a while.
Under any case, thanks for answering!