I would not infer that being placed or held in a reinforcement unit meant your relative was a problem soldier. Your relative being held in #1 CACRU (Cdn Armd Corps Reinforcement Unit) probably only means that he was there for advanced training and possibly to take special trade courses until his particular skill or trade was required in a regiment. According to the book "The RCAC and Illustrated History"(pg118), #1CACRU was set up to reinforce trained reinforcements for armoured car and recce regiments. #2CACRU served Army Tank Regiments, and #3CACRU served reinforcements for Armoured Divisions...
Special Employment Companies were set up for men who were not fit for combat for various reasons, the excellent Terry Copps book you have on Battle Exhaustion outlines this well. Most SEC units were set up to hold neurotic cases, some mental incompetents (morons). Men unfit for frontline duty but still able to perform useful rear echelon tasks. Some SEC units, I believe #19 and #20 were set up to hold and transfer men who had physical (PULHEMS) downgrades, but again could fulfill useful Line Of Communication tasks. (I don't have my copy of "Battle Exhaustion" handy or I would quote).
Taking my own Father's record as an example, he was sent to England in the spring of 1944 after qualifying as a tank driver/mechanic. He was immediately placed in #3CACRU and was held there for three months. While there he took a fitter's course. He was then transferred to a regiment in the field. After being wounded in Germany in late Jan/45, he spent three months in the hospital and then returned to his unit. However the M.O. downgraded his hearing and was classed fit for L.O.C. duties only. (From what I read in Copp's book, had it been earlier in the war, my Father's hearing loss would have been a sure ticket back to Canada)
He was transferred into #20 S.E.C. for a couple weeks until the war's end where he was placed with the (14CAR) Calgary Tanks as a mechanic again. He finished out his post-war sevice as an ambulance driver in London. While I wouldn't say my Dad was a trouble maker, he was no angel either. However, his troubles didn't make his service record until his days in London and some "unofficial" use of the King's property... they didn't send him to an SEC then, he was indeed quite fit for a Detention centre where he was confined until they found a nice big ship back to Canada for him
Bill.