The eraser seems to work on furniture, but I seem unable to change the roof height on templates I created.
Thank you for the bug post; I am unable to replicate your findings.
- Create building
 - Save template
 - Reopen building templates
 - Place building (from template)
 - Select roof
 - Adjust roof height
 
I had no problem doing this. If you have more detailed instructions how to replicate this error please provide them so we can confirm this as a bug.
r166
MAC OS 10.9.5 running VMWare Fusion 7.0.1
VMware Tools 9.8.4
This is the assertion error I get when I open the editor.
server | 0 |                         lua.code | – Script Error (lua) Begin -------------------------------
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    radiant/lib/env.luac:3: assertion failed!
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    stack traceback:
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	radiant/modules/events.luac:64: in function <radiant/modules/events.luac:64>
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	[C]: in function 'old_assert’
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	radiant/lib/env.luac:3: in function 'assert’
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	stonehearth/components/fabricator/fabricator.luac:43: in function '_create_new_project’
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	stonehearth/components/fabricator/fabricator.luac:15: in function '__user_init’
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	radiant/lualibs/unclasslib.luac:61: in function '__init’
2014-Nov-25 02:14:53.570528 | server | 0 |                         lua.code |    	radiant/lualibs/unclasslib.luac:38: in function 'Fabricator’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/components/fabricator/fabricator_component.luac:33: in function 'start_project’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/services/server/build/build_service.luac:136: in function 'add_fabricator’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	…nstruction_progress/construction_progress_component.luac:147: in function 'obj’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	radiant/modules/events.luac:14: in function 'self’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	radiant/modules/events.luac:74: in function <radiant/modules/events.luac:72>
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	[C]: in function 'xpcall’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	radiant/modules/events.luac:72: in function 'trigger’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/lib/build_util.luac:148: in function 'restore_template’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/services/server/build/build_service.luac:344: in function 'build_template’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/services/server/build/build_service.luac:343: in function 'cb’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/services/server/build/build_service.luac:334: in function 'do_command’
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code |    	stonehearth/services/server/build/build_service.luac:343: in function <stonehearth/services/server/build/build_service.luac:342>
2014-Nov-25 02:14:53.571528 | server | 0 |                         lua.code | – Lua Error End   -------------------------------
Also, it adjusting the roof seems to work once? and then not again until reload? Still not quite sure.