> The obvious workaround, don't use numbers in string variable > names, is a hassle.
The problem is that numerical alignment happens at tbl runtime, not troff runtime, and tbl doesn't have the actual numbers to work with, only your variable names. I see two solutions: either use right alignment and accept that "Page" isn't centered over the column of numbers, or write a simple macro as a tbl replacement for trivial tables that acts at troff runtime and has access to the string values.