Web app to detect and replace audio peaks

I want to detect every click in a drummer's click track (an MP3 with only beats in it) and then replace these with WAV or MP3 samples of a different click sound. The drummer click track is not in constant time, so I can't simply detect the BPM and replace samples from that. Basically I regularly use recorded backing tracks for songs and I replace the default click track (the metronome track that a drummer plays along to) with custom click samples (one WAV or MP3 sample for the first beat of a bar and another sample for the remaining beats in any given bar). Annoyingly many of these drummer click tracks are not in constant time - so do not have a constant BPM from start to finish. I want to detect every click in a click track (every peak soundwave) and then replace these with the WAV / MP3 samples, and download the final file as a MP3. Ideally I want this to be a web app. I've researched this and found it is possible in Python with various libraries. I was originally looking to create this with JS, but I believe the task is too complex for the JS web audio API. Ideally I would like to have this run as a web app - so the user can upload the drummer click track file, and then sample WAVE or MP3 sounds to replace the clicks with. This web app would do all the processing and create a final MP3 file for the user to download. Detecting the peaks seems fairly easily using the Python Libraries I have read about. Replace these peaks with the samples and creating a final downloadable MP3 I'm not sure about.