April 23rd was a generic date - probably when IRCC launched or uploaded existing applications on to the new tracking system so thousands of applicants have the same date and it's kind of irrelevant.
If I were you, I would follow the applicants from the month you had applied in and also the months before and after to understand and calculate the progress. Or you can always request an ATIP to find out exactly what they are doing.
That date appears to be generic like the OP has already mentioned. I have the same update date (the last update on my account was BG checks set to "Completed" on March 9th).
This date gets updated when you have updates about your test, oath etc.