Hi Meandtim
Welcome to the Apple Community.
Re: "train tickets .... the next day they are gone"
Seems there is a setting which hides event passes etc. when the event date has expired.
You might need to change that setting to see if your train tickets stop getting hidden after use.
ie: Scroll down to:
"How to view, unhide, or delete expired passes on your iPhone"
in the linked article below:
Remove passes from Apple Wallet - Apple Support
And if "unhiding" reveals your train tickets ...
You might want to turn this feature off in Wallet & Apple Pay settings on your iPhone.
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More info, if needed:
Add a transit card in Apple Wallet
Top up your transit card with Apple Pay
Use Express Mode with cards, passes, and keys in Apple Wallet
All the best :-)