In the interest of anyone reading this forum who wants to build this module, I should let you know that I managed to get this module to work as intended simply by removing the plastic of the header and rotating it 180 degrees as @analogoutput suggested. I am glad I was a bit cautious after the problems in my attempt on Haillant’s Simple VCA, so no ICs were harmed. I only had to replace the regulator.
Indeed, this is a Synthrotek design and not a particularly good one. There is no wet/dry blend, and the mix interacts with the feedback. Between them, there are very few usable settings, while the delay/rate pot has very limited usable travel in itself before it gets awfully noisy (not in a good way). This also means that patching almost any CV will get the rate up to the noisy setting making the sound unusable in a strictly musical sense. I could only get a decent sound when I plugged a very limited voltage in the CV input (e.g. a very slow CE-2 LFO with the depth turned all the way down) and adjusted the rate potentiometer accordingly. Still, it is not bad in these few settings. I played a few notes on a scale for a couple of minutes using a single oscillator, through a slow-modulating filter cutoff and the rate slow-modulated by another LFO, and my wife fell asleep on the couch. I knew white noise has a relaxing effect, so I guess noisy delays have that effect too? (Or it could have been the wine, I don’t know).
More importantly, it served its purpose of getting my hands wet with the PT2399, before I tried one of the nicer delay or chorus designs. I read quite a few complaints that a good fraction of the PT2399s sold in batches online at the particular auction site 
seem to be faulty, so I didn’t want to risk pulling my hair out trying to figure out the faults in a stripboard design. This particular design had a CV input (an attractive feature to try), and having a PCB would keep the variables that could go wrong at a minimum. Or so I thought!
As @Kelaifu mentioned, I was also impressed by the variety of designs at gerbster (like some Thomas Henry circuits that I could not find elsewhere), but I was a bit suspicious because I have not seen these repositories discussed in forums. I do appreciate it when people take the time to make their PCB designs open-source but I was just very surprised that they did not document these issues (let alone correct them). It just takes a minute to write on the website or repository a “beware… so and so” warning. I also noticed that the potentiometers are wired backwards from what one expects them intuitively. I guess not everybody is so diligent like @analogoutput and others in here! 