unreliable swype typing

I am trying Swiftkey. I am an old user of the defunct Swype keyboard. I can still use it, as it's installed on my phone, but there are no updates and some bugs will always exist. Still, it's more precise than Swifkey as far as i experience and the shortcuts makes your life much easier.

I thought that since Swype keyboard is not anymore produced, Swiftkey had time to improve and implement the best features of Swype, at least make a choice in the options to use them. Swiftkey looks nice with so many themes, also some shortcuts are finally implemented. But it's extremely unreliable. I type "too" (or randomly any word) and it gives me "tyuol" or some other splited nonsense short words or even autocorrects the previous word in a wrong way, even if in option i unticked the autocorrect feature. It makes me spend more time correcting and deleting unasked words than actually text. I try to swype a simple word like "ich" in german..and it gives me again some weird words or letters..i'm asking myself why? almost every sentence you use that word and still it fails..i have a constant usecure feeling in my hand that the new word will be a fail..

Also, an unexplainable unchangeable backspace function in swiftkey, of not deleting the whole word after swyping a word but only bringing the cursor to the end of the word, makes texting so slow..because very often the word is wrong, but also on the prediction/correction bar i don't find the desired word, so pressing backspace should immediately delete the word and quickly retry. So i have to press backspace long and i might delete even the previous word or part of it. Weird. Weird that there's no option to customise the backspace action.

I like new and fresh updates. That's why i'd like to switch to swiftkey, but these issues make the app unusable. Was a cool first feeling, but it's not even been 24 hours and again I am convinced to delete it.

Another thing, I am texting much more than i call and i use 5 languages. Great, that now you're not limited to 3 languages like before, but maybe also that's why it's not reliable, because very possibly when i need a word, it gives me a word of another language. Why isn't it possible to choose the language manually or set which languages to work in a multilingual keyboard? On Swype keyboard i press long space and release it on the language that i prefer. Than to quickly switch back to the last language used, i swyped shortly from Swype button to space. However i had also the choice to use multilanguages.
This would be a basic option. If i'm not wrong, Huawei phones come from the box with Swiftkey installed and choosing the language is possible. Right or wrong? So why isn't it possible on the google market app?

Can someone give me some answers about my concerns? Am I doing something wrong? My phone is made in 2018, an S9+, no way that it's too slow for this app.
I'm here and wrote this post because i would like to use the app, but please someone tell me if you have a better experience. 
I can read for hours the complaints of the users on google play, but there are no answers, no solutions to the problems. That's why i described here my experience with Swiftkey.

Thank you!