From the Guidelines

Yes, carbapenems have a greater propensity than cefepime to lower the seizure threshold.

The main risk factor associated with neurological toxicity of beta-lactam antibiotics, including carbapenems and cefepime, is renal failure, which may cause rapid and significant accumulation of these drugs 1.
Some molecules, such as cefepime, have a lower neurotoxicity threshold than other beta-lactam antibiotics, with neurotoxicity occurring in 48% of cases in patients overexposed to cefepime 1.
In contrast, carbapenems like meropenem have a higher threshold for neurotoxicity, with trough concentrations above 64 mg/L associated with neurotoxicity in 50% of patients, which is higher than the threshold for cefepime (22 mg/L) 1.
This suggests that carbapenems may have a greater propensity to lower the seizure threshold than cefepime, especially in patients with renal failure or those receiving high doses of these antibiotics.

Cefepime: trough concentrations above 22 mg/L (discontinuous infusions) or concentrations at steady state above 35 mg/L (continuous infusion) associated with neurotoxicity in 50% of patients 1.
Meropenem: trough concentrations above 64 mg/L associated with neurotoxicity in 50% of patients 1.

From the Research

The study 2 suggests that carbapenems have a potent seizurogenic effect, which may lower the seizure threshold.
In contrast, the study 3 found no increased risk of cefepime-induced neurotoxicity (CIN) in patients with a history of seizures, indicating that cefepime may have a lower propensity to lower the seizure threshold compared to carbapenems.
The study 4 compared outcomes associated with cefepime versus carbapenem therapy for bloodstream infections and found that patients treated with carbapenems were more likely to experience neurological adverse events, suggesting that carbapenems may have a greater propensity to lower the seizure threshold.
The study 5 evaluated the association between carbapenem agents and seizure activity, and found that the seizure-inducing potential of carbapenems may be directly related to their β-lactam ring structure, with imipenem-cilastatin having a higher seizure rate compared to other carbapenems.
The study 6 performed a systematic review of seizures associated with antibiotic classes and found that evidence for antibiotic-related symptomatic seizures is low to very low, but numerous reports point to an increased risk for symptomatic seizures especially of unsubstituted penicillins, fourth-generation cephalosporins, imipenem, and ciprofloxacin in combination with renal dysfunction, brain lesions, and epilepsy.

Carbapenems, particularly imipenem-cilastatin, may have a higher propensity to lower the seizure threshold compared to cefepime 2, 5.
Cefepime may be a safer alternative to carbapenems in patients with a history of seizures or at risk of seizures 3, 4.
Patients with renal dysfunction, brain lesions, or known epilepsy may be at increased risk of seizures when treated with carbapenems or other antibiotics 2, 6.