Is it possible to delete data on a cartridge, and replace it with say, a translated ROM of the same game?

I've heard in many places that it's simply not possible. But a few sources have stated otherwise, but they claim it's far to difficult and takes to much work. So, is it or is it not possible?

I'm not exactly planning on doing this, but I would still like to know. I know flash carts are a much easier, quicker way of dealing with getting a translated ROM to play on physical hardware...but I would like to keep this in mind as a second option, if ever needed.

If it is, is there any site/guide to how the process would go?

No and Yes.

No, it's not possible to erase a cartridge and replace the data with something else.

Yes, it's possible to replace the EPROM on the cartridge with a new one that can be programmed with different ROM data. You'll need good soldering skills though. It's a tedious job.