I think the thing that threw me with the sentence is the second "would".
Tatiana - I'll presume you're a Russian speaker, and thinking of the Russian глагол НЕсовершенного вида (imperfective verb) - понимать (to understand) rather than понять (to understand), and you're using it (rather than the pf) because you want to communicate regularity in the past?
If so, just stick with "understood" rather than "would understand"; the regularity is communicated by the first "would". I hope this helps!