Yeah .. it's hard to know which plants are truly low light because it's hard to know how much light someone might actually have over their tank. They might think they have low light but could be medium.
Some plants might be listed as medium light but can be grown in lower light. It may not grow as fast or not color up the way it might if given higher light.
I can't really say for sure about the Blyxa japonica since I've never grown it.
I think it depends on how much daylight and for how long a tank gets that daylight through a window as to whether it's' even low light. I think of a standard aquarium hood as being low, low light .. barely able to sustain plants. But I'm new to planted tanks and could be wrong.