Is the Sparkmaker good enough to print OO/HO small detail objects?
In general, resin printers can provide a level of detail that has to be viewed with a magnification device. The technology used in the printer will limit the resolution of the printed object. Laser based SLA printers will give the smallest resolution, while LCD panel based printers can be slightly more coarse.

The specifications on the web site for that printer indicate an X/Y resolution of 57 microns, which is 0.057 millimeters. One-sixteenth of a millimeter is quite a high resolution when it comes to 3D models.

According to the 'net HO scale is 1:87, described as 3.5 mm per foot, a peculiar comparison. Directly related to the resolution of the printer, 0.057 mm becomes 0.20 inches approximately. I suspect that an HO scale model does not require one-fifth of an inch detail level.

OO scale is slightly larger and would pose even less of a concern regarding fine resolution objects.