Not really. I assume you mean that it seems arbitrary that בא is sometimes translated as "come", sometimes as "is coming". That's done because Hebrew doesn't distinguish between the present continuous and the simple present. For clarification, the present continuous (or present progressive) is "is coming", and the simple present is "come".
Sometimes the most natural way to express an idea in English is with the continuous aspect, but other times it's more natural with the simple present. Hebrew just always uses its plain ol' present tense. :) As a result, you will sometimes translate the Hebrew present tense into the English present continuous ("is coming"), and sometimes into the simple present ("come").
Hopefully I correctly understood your confusion (just let me know if I didn't!) I'm just a beginner myself, so if any more knowledgeable people have corrections to my answer, please offer them. ^^
That was a great explanation! Hebrew is technically a simple language, but it's cultural context adds a level of intricacy which can make any language difficult to ever truly master!
I grew up in a more or less bilingual family and I've been at about caveman level reading/writing/speaking the Hebrew language for long enough I finally got embarrassed enough to refresh myself- who knows, maybe I'll get from caveman-level to toddler-level in the next decade! ;)