How would you use machine learning for peak detection?
To be honest, I don't think CNNs, RNNs and LSTM are useful for this kind of problem – a bandpass filter followed by a threshold would be.

Now, that would have three parameters:


Lower cutoff frequency
Upper cutoff frequency
threshold value


and what is usually called "Machine Learning" is nothing but finding local minima over some (loss) function with real value over a multidimensional field.
There you go – three dimensions in, find the point in that threedimensional parameter field that when used to parameterize the filter-threshold algorithm yields points closest to these you manually label.

You can very well try and solve that using neural networks! But honestly, if I was to write an optimizer for that problem, it'd probably look at the spectrum of your signal, identify the frequencies of interests through STFT, and then only sweep the remaining threshold parameter to find a good solution.