I am really confused over this. I tried looking in the support system and you have never opened a single ticket about any of this.
TLDR; What Cgam3r says is factually inaccurate and not correct.
1- You can use shortcodes in the Gutenberg editor, you simply paste it and your block will be converted into a shortcode block.
But why would you do that? Let's Review comes with actual native Gutenberg blocks. One of those blocks is literally called "Comment Review Averages". In that block you can make it show the scores of ANY post via the simple "select post" option in that block. In other words, you can literally and very easily show the averages of comments for all your posts in any page you want. It would take less than a minute to do it all, you'd simply duplicate the block I mentioned multiple times and change the block's post to a different post each time, etc.
2- See number 1, this is untrue.
3- Again, I don't know how you're adding shortcodes to your category, but you can show any review, anywhere.
I hope this info helps and that you can reconsider your review, as it is not factually accurate.
If you need any assistance with any of this or to simply speak about the plugin, you can simply open a ticket here: http://codetipi.ticksy.com