No you don't need to change anything. In-fact, you actively DON'T want the HTTP sitemap to be feeding Google a list of HTTP URLs, which I am sure you are trying to steer Google away from. Only feed Google the HTTPS URLs, delete the HTTP sitemap from search console if you can so that it doesn't keep flagging false positives, and feeding Google bad (insecure) URLs

This post from Jan 2020 seems to assume that you can still use &pws=0

https://www.business2community.com/seo/keyword-ranking-report-google-search-differ-heres-why-02275972

... but I don't know how reliable it is!

To me this depends upon the traffic build of your old domains. If they mostly receive direct and referral traffic, then the redirect idea could work very well. If they gain most of their traffic from Google, redirecting them will eventually make them stop ranking as Google don't like to rank (in the long-term) redirecting URLs

Once that occurs, your main site may gain ranking features from your old sites, but even with perfect redirects (using the mighty 301) you would still stand to lose rankings. Google will basically check how similar the last active cache of the redirecting URL is to your new page (the redirect destination). Even with a 301; if the content (in machine / Boolean terms) is highly 'dissimilar', then your new page will only receive a fraction of the SEO / ranking authority of the old (redirecting) URL. This is to stop webmasters buying up authoritative expired domains, redirecting them to themselves and gaining free ranking power

From Google's POV, a lot of ranking 'power' (authority) still comes from links. Which sites have the best links? Do other sites in the same area of the web (same theme) have more quality links? How fresh are those links? Are there any positive / negative trust signals to refract along that axiom?

When a page ranks well on Google, it is because it has recently (or historically) 'impressed the web' (thus gaining backlinks and un-linked citations). If you replace a page which has 'earned' links with another page (like a sales funnel) or redirect it to a completely different page, why should that new page benefit from the same links? The webmasters who linked to the old URL, may not have chosen to link to the new page (be it a replacement or redirect destination) so it shouldn't see loads of SEO authority coming from a past legacy

Obviously if you just change domain and the pages are essentially the same, then it's fair that those pages retain their former Google rankings. This is why Google has to validate the 'similarity' of old vs new pages (whether they replace the current content, or exist at the end of a redirect)

Be careful with your path forwards. You could have a 'great idea' only to lose most of the traffic which those domains were supplying

Obviously if the old domains which you are sweeping up, don't see much traffic from Ads or Google (SEO / organic), then you can do pretty much whatever you want with them. But if the traffic came mostly from Google (organic) then it may be tricky. It may also be tricky to redirect the domains if paid ads are served to them, as ads will often be 'disapproved' if they point to a redirecting URL (true of FaceBook and Google ads). So at the very least there would be a major overhaul of your ads campaign(s) which would be required

It depends what you mean by 'alias'. If you means configuring the old domain to properly 301 redirect all URLs from the old site to the new site (so the old site becomes inaccessible, due to serving as a redirect platform) then yes. If you mean doing something else, like pointing the old domain to your new site - other than by 301 redirects, it's probably not a good idea for SEO!

I'm still watching RankMath like a hawk. It really does look very good

No - translations don't count as duplicate content, but you should ensure that your site has a proper multiregional build-out (e.g: site.com/press-releases/artice (EN) vs site.com/fr/press-releases/artice (FR)

You should properly 'build out' the site in an international way, don't use low quality auto-translate plugins or live-translation features. You will need all your hreflang tags set up properly, so Google knows they are alternate language page variants (see: https://yoast.com/hreflang-ultimate-guide/)

See this from 2011: https://www.youtube.com/watch?time_continue=2&v=UDg2AGRGjLQ&feature=emb_logo where Matt talks about whether translations are duplicate content. AFAIK Google's stance hasn't changed loads. The translation must add value and you must use human-translated content (written by someone competent enough, that it doesn't read as if it was written by a machine)

More recently John Mu (from Google) has said that auto-translated content won't gain penalties but the rankings will suck so basically still get humans to write stuff: https://www.seroundtable.com/google-auto-translating-content-penalty-28413.html

Interestingly Google recently said that they think there may come a time in the future where auto / machine-translated content is acceptable: https://www.seroundtable.com/machine-written-content-google-guidelines-28338.html

... but as of now, it's still considered poor and against guidelines!

I would not advise starting from scratch, unless you want to lose all your followers and all the progress which has been made so far!  If you possibly can redesign and alter the name / URL of the profile, doing that would be a much better idea. The only exception to this is if, your profile has never previously performed well for you and has seen a lot of bot traffic (which may be perceived as negative by IG). If your profile has anything remotely positive going for it, keep it.