If there is a way to compare the source data with target, that would be a good feature. Then notification can be sent to alert and investigate validation issue. This kind of data inconsistency notifications will help users to rapidly pinpoint the issue on QLIK Replication. It might be a bit difficult to make row by row comparison but at least comparing the total row count of individual tables enable users to check the overall consistency.
We have built a separate process which we call counts and sums to compare record counts and perform basic aggregation on the tables from both systems based on the primary key and configurable criteria to ensure overall consistency and accuracy. Having this functionality built into replicate or compose would save people an enormous amount of QA time and give piece of mind that the tool is working as intended. I would love to have an option to run this on a scheduler in replicate or after a data load in Compose. I think this would also save a lot of support calls on your end as this would validate the data is actually making it all the way though properly.
Data validation is not currently on the Replicate roadmap. However, there is some validation functionality available with Qlik Catalog - you may reach out to your account rep to learn if this would meet your needs. Several of our customers also prefer to do validation and reconciliation with their own scripting or "independent" 3rd party tools.