Assuming your series of “ifs” could be linked, you have no law to hang your hat on. Contract law is pretty clear — the payoff is based on matches not “intended matches.” (And I don’t buy the win happens first, then the matching item is moved into position — and you would never get that in, even in the EU, since the overall code is a big time Trade Secret).
But in court, you never know. Especially EU courts.
NOT a series of “if’s” ,, the odds chip is the same in all machines , are customized by the particular casino and not all machines pay off at the same odds or rate, the display is seperate and customized for each machine with different images ... the “win” sirens/bells/whistles are triggered by the odds chip signaling the computer system in the casino of the win ,, these slots are all networked...
In the US if this “malfunction” was alleged by the casino the casino board would confiscate the odds chip out of the machine before it was allowed back in play for a determination. I suppose it could have some kind of non-volatile memory in addition to the code on eeprom to store maybe the last 100 or 500 or 100 plays ...
I know of two “error” jackpots in an Indian casino near me and have seen dozens of these reports over the last few years... It certainly seems suspicious... and smells of grand theft.
P.S. The coding is NOT a “big time trade secret” ,,you want it? Just buy a machine and dump the eeprom... or write to the Nevada gaming comission , they will probably send you the .bin file to peruse .. it’s a standardized chip with the only allowed modifications being the actual odds payout table ,, the standards are published ...