Space exploration mod delivery cannon is a special case, since low enriched uranium wasn't there before and is needed for fuel cells, I can no longer deliver fuel to power my outposts. Delivering weapons grade fuel is now possible however, though it shouldn't be. The was SE makes recipes for delivery cannon is somewhat special I think, tried looking through the code for it, but I'm so confused. Can you help me turn the lights back on?
I do not play SE (or other overhaul mods). Looking into code of other mods (especially big ones) take a lot of effort. That is why I have no plans to support overhaul mods.
I also suggest making a script.on_init() function in control.lua to change out the highly enriched uranium into low enriched uranium. Something like checking all entities with inventory if highly enriched uranium exists, count it, remove it, add replacement item...loop through all entities until done.
That does not sound a good idea at all.
Some players (including me) do allocate some chests to store the original U-235 (now HEU). Your proposal means those chests will be "polluted" by having both HEU and LEU in all of those chests, which will take extra manual effort to clean up. Thus undesirable.
Another point is what U-235 before : HEU after : LEU after
ratio do you want? Currently it is 1:1:0.
If you want it something like 1:(1-r):r, some players are going to complain that there is a loss of overall U-235 contents.
If balance of U-235 contents is required, the ratio would be like 1:(1-r):20r, there will be more items than before. Especially a problem if the chests are full (having all but one chests being full is typical in such kind of storage area).
So such proposal is making more trouble than its good.