Sorry I didn't get back to you sooner.

I deleted the folders as requested and restarted PingPlotter. Yes it did act as if it were a freshly installed program on restart, but it crashed again.

Crash reporter logs:
Process: PingPlotter [8478]
Path: /Applications/PingPlotter.app/Contents/MacOS/PingPlotter
Identifier: com.pingman.pingplotter.mac
Version: 5.9.3 (4481)
Code Type: X86-64 (Native)
Parent Process: ??? [1]
Responsible: PingPlotter [8478]
User ID: 502

Date/Time: 2019-09-12 08:07:08.675 -0700
OS Version: Mac OS X 10.11.6 (15G22010)
Report Version: 11
Anonymous UUID: 0C19D79C-EEB8-EABB-FA34-F5DF13FC087B


Time Awake Since Boot: 380000 seconds

System Integrity Protection: enabled

Crashed Thread: 0 tid_160b Dispatch queue: com.apple.main-thread

Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes: 0x0000000000000001, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY

Thread 0 Crashed:: tid_160b Dispatch queue: com.apple.main-thread
0 liblitehtml.dylib 0x00000001081f4165 litehtml::html_tag::draw_children_box(void*, int, int, litehtml::position const*, litehtml::draw_flag, int) + 213
1 liblitehtml.dylib 0x00000001081f46fd litehtml::html_tag::draw_children_box(void*, int, int, litehtml::position const*, litehtml::draw_flag, int) + 1645
2 liblitehtml.dylib 0x00000001081f59f6 litehtml::html_tag::draw_stacking_context(void*, int, int, litehtml::position const*, bool) + 598
3 liblitehtml.dylib 0x00000001081cc438 Draw(DocContainer*, int, int, litehtml::position) + 40
4 ??? 0x0000000107f67a68 0 + 4428561000
5 ??? 0x00000001083cf416 0 + 4433179670
6 com.pingman.pingplotter.mac 0x0000000100dff621 mono_jit_runtime_invoke + 1441
7 com.pingman.pingplotter.mac 0x0000000100efca24 mono_runtime_try_invoke + 148
8 com.pingman.pingplotter.mac 0x0000000100eff8c6 mono_runtime_invoke + 38
9 com.pingman.pingplotter.mac 0x0000000100ff4add native_to_managed_trampoline_10(objc_object*, objc_selector*, _MonoMethod**, CGRect, unsigned int) + 333
10 com.pingman.pingplotter.mac 0x0000000101026711 -[LiteHtmlSharp_Mac_LiteHtmlNSView drawRect:] + 129
11 com.apple.AppKit 0x00007fff9d9137be -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 1331
12 com.apple.AppKit 0x00007fff9d913156 __46-[NSView(NSLayerKitGlue) drawLayer:inContext:]_block_invoke + 242
13 com.apple.AppKit 0x00007fff9d912caf -[NSView(NSLayerKitGlue) _drawViewBackingLayer:inContext:drawingHandler:] + 2403
14 com.apple.AppKit 0x00007fff9d912341 -[NSView(NSLayerKitGlue) drawLayer:inContext:] + 108
15 com.apple.QuartzCore 0x00007fff96fd9a05 CABackingStoreUpdate_ + 3494
16 com.apple.QuartzCore 0x00007fff96fd8c59 ___ZN2CA5Layer8display_Ev_block_invoke + 59
17 com.apple.QuartzCore 0x00007fff96fd8645 CA::Layer::display_() + 1565
18 com.apple.AppKit 0x00007fff9d911318 _NSBackingLayerDisplay + 641
19 com.apple.AppKit 0x00007fff9d903878 -[_NSViewBackingLayer display] + 818
20 com.apple.QuartzCore 0x00007fff96fca38d CA::Layer::display_if_needed(CA::Transaction*) + 603
21 com.apple.QuartzCore 0x00007fff96fc9eb5 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 35
22 com.apple.QuartzCore 0x00007fff96fc9389 CA::Context::commit_transaction(CA::Transaction*) + 277
23 com.apple.QuartzCore 0x00007fff96fc8fd4 CA::Transaction::commit() + 508
24 com.apple.QuartzCore 0x00007fff96fd4863 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 71
25 com.apple.CoreFoundation 0x00007fff9ce26fc7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
26 com.apple.CoreFoundation 0x00007fff9ce26f37 __CFRunLoopDoObservers + 391
27 com.apple.CoreFoundation 0x00007fff9ce05e48 CFRunLoopRunSpecific + 328
28 com.apple.HIToolbox 0x00007fff94c38935 RunCurrentEventLoopInMode + 235
29 com.apple.HIToolbox 0x00007fff94c3876f ReceiveNextEventCommon + 432
30 com.apple.HIToolbox 0x00007fff94c385af _BlockUntilNextEventMatchingListInModeWithFilter + 71
31 com.apple.AppKit 0x00007fff9d7aadf6 _DPSNextEvent + 1067
32 com.apple.AppKit 0x00007fff9d7aa226 -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 454
33 com.apple.AppKit 0x00007fff9d79ed80 -[NSApplication run] + 682
34 com.pingman.pingplotter.mac 0x0000000100cfdb99 xamarin_dyn_objc_msgSend + 217
35 ??? 0x00000001066a3a25 0 + 4402592293
36 ??? 0x00000001017cae79 0 + 4319915641
37 com.pingman.pingplotter.mac 0x0000000100dff621 mono_jit_runtime_invoke + 1441
38 com.pingman.pingplotter.mac 0x0000000100efafdf mono_runtime_invoke_checked + 127
39 com.pingman.pingplotter.mac 0x0000000100f01e5e mono_runtime_exec_main_checked + 110
40 com.pingman.pingplotter.mac 0x0000000100d5e1d9 mono_jit_exec + 297
41 com.pingman.pingplotter.mac 0x0000000100d611d4 mono_main + 11156
42 com.pingman.pingplotter.mac 0x0000000100cfe469 xamarin_main + 1305
43 com.pingman.pingplotter.mac 0x0000000100cff434 main + 36
44 libdyld.dylib 0x00007fff8e9615ad start + 1

Again it continues for several pages...