We’ve already argued that tieing anything into explorer rank is a bad idea considering how broken and outdated the explorer rank system is, we had more votes on getting a more linear system than this forum at one point, but that forum has since been abandoned Mission Board: Linear Progression hopefully it’s been at least considered or worked on, although we don’t know anything since it received no staff commentary, as for staff adjusting the rates check the discord, or be active on pmu at all, sciz and pencil have said it multiple times if I remember correctly.
Edit: I think instead of a shiny charm having shiny spawn rates tied to explorer rank is a great idea (Since explorer rank is the equivalent to the pokedex in the main series), but I believe linear progression of explorer ranks should be added first.