After the feedback session I got several pieces of advice on how to improve my concept technically. So I tried to review what I currently had and try to implement the changes.
First was about using various types of cards. To do that I came back to the very beginning and asked myself again about the objective for the game mechanics. Since we’re playing mostly to build the long path to our goal, I have the following balance to achieve:
“Path cards must not be received too easy. So that players must be encouraged not to just collect, but fight for them. But at the same time it mustn’t be too hard since there will be several rounds till the final victory”
I am sure about how to stop players from hoarding cards. That is to limit the number of cards they have to 2, what is left fron the first game draft.
To diversify playable cards I decided to introduce 2 types – exclusive ones only for scorpion or grasshopper path and neutral, which can be used to fill in path slots of any player. Since we have 5 path slots available, I tried different options for card type proportions: 4 excl. to 1 neutr., which I found not relevant, and 3 excl. to 2 neutr., which for now work as a basic proportion. Because the game is not likely to stagnate because of trying to win over too many exclusive cards.
Introducing neutral cards will make path building faster and easier; can be used as a minor trophy in “belive me or not system”, but potentially can speed up the game too much.
The new positioning scheme now looks like this:

Bonus cards:
Another card type worth implementing are bonus ones. They give some special features and can help to overcome stagnating states. There will be 4 of them. First, I thought that they should be distributed randomly from the deck. But then I understood that that won’t be too fair; bonuses can occupy all 2 card options that you’re allowed to have at hand. So the best solution is to make them as trophies for the main tricking mechanic.
For now there are:
2 “this card can fill one path slot”
1 “Opponent has to empty one path slot” (the card goes beck to the deck)
1 “+1 card at hand till the end of the round”
Rounds
New idea develops from the alternative first draft concept, where I wanted to use short path cards as round markers. I was advised to use just 2 cards for that with a flip system. So now round markers will be cards that fit the narrative as well. I’ll call them arrow cards and they will have an image of arrow, turning each time towards the scorpion and /or grasshopper. Like timer or trigger of the whole mechanism. Whoever wins 3 rounds will activate the mechanism.
Believe me or not
Advice in this area was to think about rewarding players rather than punishing them. So I asked myself a question: What behaviour type should be rewarded? Since the game is connected to the book episode, where the Phantom was tricking Christine, I thought that players should be rewarded for tricking their opponent the most and get the least or no profit from telling the truth or being busted. I’ve been thinking for a long time on the rewards and profits and finally came up with the following scheme, which, I believe, is balanced enough. That will not only allow to get bonuses, but to work as a ‘trading’ mechanism to make players shuffle or exchange exclusive cards.

Having all these decided, I managed to come up with mostly final draft of the ruleset.
https://drive.google.com/file/d/1sdrmjr4y7qBctalAZaZziJGPzj0-rKQ2/view?usp=sharing
For the playtest I have one major question, that is what is the minimum of exclusive cards a player must have. Either minimum of 1 or obligatory have all 3.