"understood deeper" is grammatically correct and can be used in written English.
It means to understand something in a more profound or extensive way. Example: After studying the novel for weeks, Sarah finally understood the underlying themes and messages, allowing her to appreciate the story on a deeper level.
I don't think Charley understood deep down the genius he was.
Godard understood deep-focus effects as just that — one effect among many in a filmmaker's panoply, one that was not inherently praiseworthy with respect to editing or nonediting.
An open and sensitive attitude is described in terms of "bridling pre-understanding" which involves a willingness to listen, see and understand deeper meanings of the phenomena through a distancing and reflective attitude to unfamiliar experiences [ 22].
What readers require to understand deep crises like European debt is something else.
Cashman likely understands, deep down, that a great achievement of the season was probably keeping so many older players healthy and productive.
So, even though the stakes are pretty high in this situation — total annihilation — I think these young women understand, deep down, that the stakes are always that high, for everyone.
That the actual practice of meritocracy mostly involves a strenuous quest to avoid any kind of downward mobility, for oneself or for one's kids, is something every upper-class American understands deep in his or her highly educated bones.
Seemingly more plausible is the idea that serious fiction is not enjoyable because it is difficult, requiring intellectual effort to untangle complexities of plot and syntax, to appreciate obscure allusions, or understand deep philosophical themes.
No one understands deep-fat frying better than Nikki: her calamari, often served straight onto a wooden board from the hot oil, are the freshest and crispest you will ever try.
Teaching to understand deep feelings or cultural references will require entrepreneurs who understand local humans.
