I'd like to start off and say, that GOOGLE WILL NEVER give you an SEO tool to tell you precisely how to rank your website, indirectly maybe..if you read between the lines ( I believe this is what the best Seo guys are good at) - it would hurt their paid advertising platforms so much, it may tell you how to improve user experience and data about keywords that can help you with traffic and user experience, and could indirectly increase ranking. I think this is the only form of SEO Google is happy with because is focussing on quality instead of ranking manipulation.
Given that Semrush and Ahrefs are all somewhat based on tools provided by Google and independent research they aren't 100% either. I realize these guys have some independent research on their tools - but guess what guys its always going to look good, they are selling a product you know. <--- one that threatens Adwords.
There will never be a clear answer to this question it's simply how Google protects its search engine quality and more importantly Adwords. Now I'm not saying all these tools are wrong, I'm just saying not 100% we always tend to use a combination of tools for a specific goal and cross-reference the data to make changes. It's what I've found works the best but it's not 100% not close.
Also, Google changing ALL the times do you think your tools are also changing all the time - I don't think they have the manpower to do so, I think some try but fall short, a lot of times it's best to play it by ear 9 a/b testing )
PS if anybody ever finds out how to 100% rank your website no1 every time on Google and it gets out you'd bet you will see massive changes in Google's algorithm. They are simply not going to allow AdWords to take a knock because people who would have used AdWords know how to rank easily - or lose users (searchers) because SERPs are spammed with low-quality content ( which will lose them, advertisers, too ).