You can explore the feasibility of directly checking this in the segmentation criteria, itself. This segment can be used in a batch journey (say, that runs daily) Target users who received a welcome email 30 days before today and there is no app login event detected. 

can you do a profile lookup and see if the identityMap has the namespace populated that you are looking for ?

For unitary journeys (event based and audience qualification), emails will be sent to addresses in seedlist at the time of first send only.

Event-based journeys in AJO are designed to trigger personalized customer experiences based on real-time events or interactions. This feature is ideal for sending notifications in response to specific customer actions or behaviors, such as making a purchase, abandoning a cart, or updating their prof...

Kindly check if discover.newProduct value is added to the event type attribute as enum / suggested values (Reference - https://experienceleague.adobe.com/en/docs/experience-platform/xdm/ui/fields/enum)  If so, try creating a new event and see if it shows up. As an alternative, you can use advanced m...

Kindly log a support ticket for this.

You can create a batch segment leveraging the attributes from message feedback event schema and accordingly suppress it, within the journey. Assumption is, profiles had the message node processed in journey. However, you need to wait for the daily batch segmentation job to be run before you can use ...

It will be on the following lines if (a=="1") then ("XYZ") else ( if (a=="2") then ("XYZ") else ( if (a=="3") then ("XYZ") else ("No Segment") ) )

Can you share the screenshot of what error you are running into ?

you will need to access it via the message node or the simulate content option. Referenceshttps://experienceleague.adobe.com/en/docs/journey-optimizer/using/landing-pages/create-lp#test-landing-pagehttps://experienceleague.adobe.com/en/docs/journey-optimizer/using/landing-pages/get-started-lp