Hi @GSignorelli would you mind adding more context on what does "does not solve the problem" mean for you? Does it not function by design ie. you're for looking for different functionality or are you experiencing a technical issue?
PS. If you're up for using 3rd party tools then Outfunnel's app connector features a 2-way HubSpot-Mailchimp integration (disclosure: I am co-founder). It syncs either all new HubSpot contacts to MailChimp, or only those you specify with a List. And it also syncs email engagement back to HubSpot.