Actually someone asked a similar qusestion on Discord.
And I quote:
If you are wanting to edit them, the only way I know of is to fork the open source project, make your edits, and then compile and install your forked version. But you are then stuck at that version. What are you hoping to accomplish, maybe there is another way to do it.
EDIT: If you decide to go that route this may help.
Thats a lot of work and your going beyond my knowledgebase on modifing Graylog Frontend. I ended up using Grafana. This is used for metrics and Logging ( i.e., Log indexed from Opensearch) for my convenience.