These are rough guidelines for judging quality at 1x. The number of PI errors and failures (both of which are correctable and thus harmless up to a certain amount) grows at faster reading speeds.
Your scan is far below acceptable PI error levels (9 vs. ~280) and PI failures (5 vs. 16-32) and the total numbers of errors and failures are very low; this allowed me to say you have an excellent burn without seeing the full scans.
You don't need to lower your writing speed, unless you are a complete perfectionist.
Take a look at other threads where scans are posted and compare if you want to see how similar TYG01 media burns in other 1620s. Here are some scans to show you how I would rank quality. Top to bottom:
1, exceptional. Under 100 total PIF, maximum 3.
2, excellent. Under 500 total PIE, maximum 6. This is probably the most similar to what you have.
3, good. Some clustering of errors at the end, but nearly all readers and players would have no problem reading that.
4, marginal. Jitter and PI errors growing at the outer edge, significant amount of PI failures at the end that may interfere with reading. The disc is perfectly readable, however, it might not be in another drive. I wouldn't trust it for critical data. In fact, I never trust any single disc for critical data