3 different energy systems in play for 500m sprint.

Chart from here (not an endorsement)
https://metrifit.com/blog/understanding ... -training/
Training can extend the duration of output for your anerobic systems. But your anaerobic systems will run out of gas before your 500m ends leaving your split fading. This is not a problem, it's how your body works. The World Rowing Indoor Championships 500m results include graphs showing how splits change over time. Look at the winner here. His split starts at 1:08 and falls to 1:22 by the end of the race.
https://worldrowing.com/event/2025-worl ... s-rankings
For a trained athlete a 500m erg sprint is about 50/50 aerobic/anaerobic. ( Based on a 500m erg sprint being comparable to running 400-800 meters. By measuring the energy byproducts of the various energy systems this study found "Aerobic to anaerobic energy system contribution (AOD method) to the 400-m event was calculated as 41% - 59% (male) and 45% -55% (female). For the 800-m event, an increased aerobic involvement was noted with a 60% -40% (male) and 70% - 30% (female) respective contribution."
https://researchoutput.csu.edu.au/ws/po ... 208029.pdf )
To max your 500m sprint you need to train your anaerobic systems more heavily than someone who is 2K focused. 2K is roughly 80% aerobic.
(1) Strength Training
(2) Repeated short intervals
Then you need to improve your aerobic output with a combination of long/slow and hard sessions.
And do all this without overreach/overtraining.
Here is your training schedule with a very rough set of changes that could meet those goals, but many others will work. As you know from strength training don't work the same muscles hard 2 days in a row, rowing works both upper and lower body and have at least one rest day per week.
Monday- Upper body strength training then do Rowing Tabata intervals like 8 sets of (20 seconds max, 10 rest)
Tuesday - Endurance row, 90 mins at conversational pace (your long duration row, will be about 15-20km but keep it zone 2 conversational)
Wednesday - Rest, some walking
Thursday - Lower body strength training; Rowing on erg 6x4mins with 3 mins rest
Friday - Endurance row, 45 mins at conversational pace (about 10km, much more and you're too fast)
Saturday - Rowing on erg 2x20mins threshold pace
Sunday - Endurance row, 45 mins at conversational pace (about 10km)
This intense schedule is not long term sustainable, but will give you improvement in 500M time in 4-6 weeks. After 4-6 weeks you need to adjust to less intense. 3 hard days, 3 zone 2 days. Total time roughly 6 hours/week.