[SalesForce] Lookup data from a custom object from a formula field

If I understood correctly, this might help:

AND(LEN(Market__c) > 0, VLOOKUP( TEXT(Market_Statuses__r.Market_Status__c) , Market_Statuses__r.Name , Market__c ))

The functionality that you are looking is not possible using Process Builder at this time. I believe it might be possible in the near future with enhancements that are coming in the next releases, but I cannot assure you of that.

You will have to rely on code in order to achieve it. I have some code that might help you.

Here is what you will need for the code:

1. Add field to Opportunity Object called "Last Status Change" (Date Time)
2. Add formula field (name it "Time in current Status") to Opportunity object with the following logic: IF(ISBLANK(Last_Status_Change__c), NOW() - CreatedDate, NOW()- Last_Status_Change__c)
3. Create a new Custom Object called "Opportunity Status Change"
4. Add the following fields to this new object: Opportunity (Lookup to Opportunity) Status (Text) Time in Status (Number)

Create the following trigger on the Opportunity Object:

 trigger trgOppTrackStatusTime on Opportunity (after update)  {
        Map<string,Opportunity_Status_Change__c> metricByKey = new Map<string,Opportunity_Status_Change__c>();

        for(Opportunity_Status_Change__c m : [SELECT id, Status__c, Opportunity__c, Time_In_Status__c FROM Opportunity_Status_Change__c WHERE Opportunity__c IN :trigger.newMap.keyset()])
        {
            metricByKey.put(string.valueOf(m.Opportunity__c)+string.valueOf(m.Status__c),m);
        }

        List<Opportunity_Status_Change__c> metrics = new List<Opportunity_Status_Change__c>();
        string key = '';
        Decimal hours;
        for(Opportunity o : trigger.new)
        {
            String oldStage = trigger.oldMap.get(o.Id).Operations_Status__c;
            String newStage = o.Operations_Status__c;
            Boolean stageChanged = oldStage != newStage;

            if(stageChanged)
            {
                hours = o.Time_in_current_Status__c;

                Opportunity_Status_Change__c temp;
                key = string.valueOf(o.Id)+string.valueOf(trigger.oldMap.get(o.Id).Operations_Status__c);
                if(metricByKey.containsKey(key))
                {
                    temp = metricByKey.get(key);
                    temp.Time_In_Status__c += hours;
                }
                else
                {
                    temp = new Opportunity_Status_Change__c(
Name=trigger.oldMap.get(o.Id).Operations_Status__c,
                                                Status__c = trigger.oldMap.get(o.Id).Operations_Status__c,
                                                Opportunity__c = o.Id,
                                                Time_In_Status__c = hours
                                             );
                }

                metrics.add(temp);
            }
        }

        if(metrics.size() > 0)
            upsert metrics; }

If the code fails to save, provide me the error and I will provide an update.

Good Luck!!