Well, there is a converter, but I don't recommend it for EAs generated from fxDreema. This one is for other EAs 🙂
MT4 and MT5 have some differences, especially in the past. Now they are very close, but this was not always the case. Most of the time I am trying to make blocks to look and work the same way in the MQL4 and the MQL5. Blocks can be copied between projects, but some old blocks would not work properly if you copy them between those two languages. And now that MT4 is abandoned from MetaQuotes, I don't know if I will ever make both parts of the builder equal 🙂
Oh... there is actually a limit of 10000 blocks in some settings, but I really want to put it to like 1000. I know that some people have even more than 2000 blocks and I think that this is not good. For me this is bad practice.