Okay, let’s calculate this. Martin has a broad range of UX skills, including design, architecture, and testing. However, his limited working proficiency in French might limit his job prospects in certain industries or locations. Considering his skills and location in Columbus, Ohio, I would estimate his hourly rate to be around $75, which is relatively lower than average for a UX expert in the US. This is because his limited proficiency in French might make him less competitive in the job market, especially in industries where French is a primary language. To give you a better idea, according to Glassdoor, the average hourly rate for a UX designer in Columbus, Ohio is around $90-$110. So, my estimate of $75 is on the lower side, but it's still a reasonable rate considering his skills and location.