Whilst Energylandia does benefit hugely from EU funds, they would not necessarily struggle if it was lost.
The original grant was only for investments up to this year (including the Vekoma Mine Train, which is on site but hasn't started construction yet, and I personally doubt would open this year, especially with Covid). However, they did successfully apply for more funds, which is helping them "accelerate" plans they had for the next few years, which has included the building more accommodation, and further expansions. Should those EU funds no longer be made available, their investment would likely still be large, but just more spread out.
If the country's homophobia increases further, it would be interesting to see how badly tourism is hit, and how it would affect the park. I don't know how many of their visitors are international, but they certainly have got the attention of the enthusiast community, which no doubt helps in drawing more people in. This is particularly prevalent with Zator being just inside a region that's declared itself LGBT-free. A drop in visitors could hit the park harder than them not having access to EU funds.
Obviously what happens to Energylandia pales in comparison to LGBT rights in Poland.