I think you need to know (and feel) how things work. Indicators are arrays of data, what the EA knows are all indicator points in the past - there is 1 point with value for every single candle. So RSI can move up/down in the current candle, but when that candle ends, RSI freezes at it's last state and only this value remains.
So how to know when RSI goes from 75 down to 70? It depends, for what time? The easiest thing is to look at the previous candle and the current candle. Or in the last X previous candles? Or you don't care if it reached 75, you may want it to just cross the 70 mark, which can be detected easily - by looking at what was the last RSI value and comparing it to the current value. Or Looking at the value in the previous tick and comparing it to the current tick (if it was above 70 just a while ago and now it is below 70, then it crossed below). The last thing is also a little bit tricky, because this event may repeat few times in few seconds, because the price always moves up and down.
In short - it depends. What I posted above is some easy way to detect such a crossovers, but you may have different requirements, or none, as very often we don't know what we really want, or the thing we think we want can be made in much simpler way.
So... what calculations do you need exactly? But looking at your project... I don't know it looks too weird for me to use tens of blocks to make something that can be explained simply as "crossover".
I can suggest to play with Condition block and blocks in "Indicators" category a little bit. For example, place "Indicator rise" -> "Draw arrow" and see what will happen. Then try something similar with another block. Also use "Indicator tester" to see how indicators work, what values they give to the EA. All this in Visual backtest mode 🙂
