Vital is effectively NOT open-source, the source available on github is a single snapshot of the source as it was when 1.0 was released, it has not been updated since, and 1.5.5 is vastly different.
Another very powerful (but now old) free softsynth is Synth1 by Daichi Laboratory[1][4]. If you look around a bit you can find literally tens of thousands of presets for it[2], which then spawned the excellent Synth1 Librarian which helps bring some sense to this huge library [3]
Helm and Surge XT are great synths (and effects in Surge's case). When my nephew wanted to dabble in audio production, I used them to beef up his free copy of Ableton Live Lite.
Helm has some of the simplest modulation among free synths. All the modulation and its strength is visible out front without needing a mod matrix. Pigments is the best among non-free synths, but I would still use Helm if I didn't have all the softsynths I've collected since I depended on it years ago.
Most digital audio workstations (DAWs) support instrument and effect plugins. The industry has largely settled on the VST interface for this [1]. On Macs it's a bit more complicated [2], I believe you can use VSTs, but there's also Apple's AU plugins and AAX.
Logic Pro should support AU but not VST I think. There's an entire industry that makes and sells these plugins, preset packs, sample packs, and other services. For example, Roland makes a pro VST/AU plugin called Galaxias [3] which requires a subscription but gets you access to near perfect software reproductions of nearly their entire synth lineup.
Synth designers are very opinionated, so they all sound different or make different choices that affect how different people get along with them. They're like DAWs that way. Lots of people swear by FL Studio, I can't stand it.
Give Helm a try. It's the only way to know if its opinions mesh with your own.
Pretty sure EMACS beat Kubernetes to the punch. This Helm, too, is pretty old now.
Complaining about names is ridiculous. There are only so many names to go around, and there's almost no overlap in use-case or userbase between a synthesizer and a throwaway piece of business software for Yet Another Soulless Cloud Ecosystem.
Naming things isn't hard. What's hard is that people feel possessive over English words. You probably share your name with hundreds of thousands of people in your country.
Comparing names of products to names of people simply doesn't make sense. Ideally you want to pick a name for your product which stands out and people will remember. You shouldn't need to clarify by saying 'use Kubernetes Helm' or 'use the synthesiser Helm'.
However people aren't usually named this way, and so you cannot compare names this way.
If I was looking for a virtual synth deck and came to you asking for a recommendation and you said Helm but actually meant the Kubernetes Helm not the synth Helm, you would have a very solid point. But you would also be an idiot.
If you came into the comments section to discuss Kubernetes Helm before opening the link and understanding what it was referring to, then that's on you not the project.
https://vital.audio/
https://github.com/mtytel/vital