ive tried mcc tool chest on my ps3 worlds and it didnt work, i believe that it takes all blocks that arent part of the original seed and removes them and puts the same java seed over it. my world was generated around 2017 near tu53 xbox but on ps3. i have some screenshots of how bad it is. if you need i can also source some images from the ps3 world
I have seen tools but many are either dodgey or probably require a lot more effort. Otherwise like Webrosc said you really can't, PS3 and other Legacy Console versions (so those that aren't PS4/Xbox One/Switch, Pocket Edition or Windows 10 all work together as Bedrock was designed to make them all work well and as they have similar hardware and game engine support it's easy to develop for them, PS3 and other systems are very complex and also outdated consoles). Java, Legacy Console and even Bedrock have different code and are designed differently. Bedrock and Java you sort of can with DragonProxy but otherwise the versions are far too different making it not worth the trouble or impossible.
So while their answer might have been straight forward they aren't wrong.