Based on 

 and https://github.com/MinecraftForge/MinecraftForge/issues/5560

 seems that modders should not modify block haverst level of other mods.

 

BUT

 

In my mod https://github.com/yanny7/StoneAge I have to adjust harvest level of vanilla blocks. Does someone have good idea how to implement this and does not break other mods?

 

another thing is that I cannot use setBlockToolSetter because it is static and now I am working on sequel to first mod where I need also adjust harvest levels ... I used reflections to modify them, but I dont like this approach. Is there better way how to do this?

32 minutes ago, Yanny7 said:

I used reflections to modify them, but I dont like this approach. Is there better way how to do this?

I doubt it. All of those properties are final, now.

Maybe move all of this modifications to central place (my API mod) and from there based on registered block changes do it at once and with possibility to disable it. At least this can be easily disabled in one place