Please do not post your question in multiple channels per the rules at #welcome-and-rules. It creates confusion for people trying to help you and doesn't get your issue or question solved any faster.
Cf DNS is ridiculously fast globally, and going much higher then that would delay your changes by a ton/at some point Resolvers would drop it when it's not being used anyway
I'm looking for a open-source repo for a fairly big project running on cloudflare workers, to learn how it's structured. If you know any, please share.
No. Even though they have Cloudflare compatibility, they still have a lot of differences with Cloudflare (support for different node modules, different runtime, other smaller differences) so Wrangler is still going to be a more accurate representation of the Cloudflare Workers runtime running in production.