If pinholes are properly cleaned up and painted from both sides then it should be ok. But I'm more bothered about the strength of your finished welds. If it is all a series of small tacks then it might be very weak. The weld does need to penetrate sufficiently and that includes penetrating the last 'tack' that you did.
As I said earlier I can't get a good weld with my welder on lowest power so suggest you try a bit more power and/or wire speed. Try holding the welding nozzle at a low angle and trailing the weld behind it. Sometimes a poor weld has to be repeated, with more power, more weld-metal and creating a wider bead.