The frequencies were in nominal range. The lowest was around 49.7, the highest about 50.6, both of which are within the allowed range of frequency (47.5 - 52.5 is the absolute emergency range, 49-51 is the nominal range, before you start capping power to or from customers).
Romania had a power blackout for a bit, but everything worked as intended and the romanian grid blacking out didn't pull in the rest of the european grid.
A partition between power grid is acceptable to preserve the largest amount of the grid remaining functional. Marrying the partitions together is bothersome but not something that takes forever (took 1 hour in this case).
While 49.7 is very low, most of your devices will not notice and will be fine. Most industrial equipment is largely already coded to handle frequency shifts in favor of keeping the grid stable.
I understand that some equipment, such as consumer grade solar panels, already disconnects at 49.8, and one early analysis I read[0] said that that in fact exacerbated the problem somewhat on 8 January.
Power producers != Consumers for small devices like consumer grade solar panels, especially if the inverter is too cheap to handle a frequency excursion.
Romania had a power blackout for a bit, but everything worked as intended and the romanian grid blacking out didn't pull in the rest of the european grid.
A partition between power grid is acceptable to preserve the largest amount of the grid remaining functional. Marrying the partitions together is bothersome but not something that takes forever (took 1 hour in this case).
While 49.7 is very low, most of your devices will not notice and will be fine. Most industrial equipment is largely already coded to handle frequency shifts in favor of keeping the grid stable.