Personally, I would not use the travel card itself to validate with the customers. I would use research methods to understand your customers and validate your roadmap.
Questions such as: "Let me know the last time you did X. How did you get started? What initiated it? What was your goal? What steps did you take? What worked well for you? What problems did you have? "Using these types of exploratory research questions, you get the data you need to validate your roadmap for milestones, needs and issues.
In addition, I would add an observation. Observe what your customers are really doing.
In the end, a customer journey map must be an artifact that represents what you know about your customers and what you get through the search.
Nothing wrong or bad to start with a temporary card as you did. I am wary of using it or your preconceived card to validate it because it can skew or direct customers. Open interview questions will discover their needs that you can then compare to your map.