Does changing the CMS affect current ranking ?

Hi BHW people,
We have built a custom CMS based on JS.
We have got different opinions about how much google likes these types of CMS's, some say it has no problem with it and some say that as it has to always render the JS to plain HTML is not optimal.
This is, besides the time, developers spend on maintaining it.
Our websites are live since 4 months and we barely get any organic traffic although we have full time in house content writers and we have invested quite some money in backlinks (good quality and niche related ones)
Our niche is not almost not competitive at all, there is traffic with low competition keywords.
We come to a point of thinking that we would rather switch to wordpress.
My questions to you are:
1 - Does the CMS type has an effect on ranking ? (all URLs are indexed)
2 - Does switching the website to wordpress (changing the theme and design but keeping URL structure and content) can change current ranking ? ( make it worse)
Thank you

Of course, it will affect your site at least because different CMS has different meta tags, content formatting.

Yes but only for a bit you’ll be able to bounce back soon

I think you shouldn't drop in rankings at all if you keep the same seo structurelike the url, title, h1, information, content etc.